Trimming the Scales: Unveiling the Impact of Lifestyle Interventions on Weight Reduction in Overweight and Obese Adults-A Comprehensive Systematic Review and Meta-Analysis

Abstract

Background: The review evaluates the impact of lifestyle interventions, including diet and exercise, on weight reduction to mitigate obesity's health risks and achieve sustainable weight loss in adults. Methodology: A comprehensive literature search was conducted across three major databases: PubMed, Google Scholar, and institute Library e-Resources, resulting in the identification of 3018 relevant studies. After applying inclusion criteria, 42 trials were selected, with 15 meeting the criteria for meta-analysis. Utilizing rigorous statistical methods mean differences between intervention and control groups were calculated with a 95% confidence interval. Heterogeneity was assessed using the I2 statistic, and potential publication bias was evaluated through forest plots and funnel plots. Results: The review encompassed a total of 2062 individuals, with an average age of 42.8±9.4 years. Our analysis revealed an overall effect size of -1.78 kg (-2.2%, -1.277%), indicative of significant weight reduction attributed to lifestyle interventions. Furthermore, our investigation unveiled variations in the effectiveness of interventions based on study duration and mode of delivery. Symmetric funnel plots suggested a low risk of publication bias, enhancing the credibility of our findings. This review underscores the importance of lifestyle treatments in weight management and highlights their accessibility and availability in recent years. Conclusions: Our findings highlight the substantial impact of lifestyle interventions on weight reduction, demonstrating significant efficacy across diverse populations. The variations in effectiveness based on study duration and mode of delivery emphasize the need for tailored approaches in obesity management programs.

Introduction

The global prevalence of obesity has reached epidemic proportions, affecting individuals across all age groups and socioeconomic strata.

With more than one billion people worldwide classified as obese, the associated health and economic burdens have become a significant concern for public health authorities and policymakers alike [1].

Overweight and obesity are major risk factors for chronic non-communicable diseases (NCDs) such as hypertension, hyperlipidemia, type 2 diabetes mellitus, cardiovascular disease, metabolic syndrome, high cholesterol levels, and cancer.

Elevated body mass index (BMI) significantly contributes to the development of these NCDs, including hypertension, and is associated with an increased risk of all-cause mortality [2].

The World Health Organization (WHO) warns that if prevention and treatment measures are not improved, the worldwide economic cost of obesity could soar to a staggering $4.32 trillion annually by 2035 [3].

The U.S. Preventive Services Task Force recommends screening all adults for obesity and providing intensive behavioral interventions to the approximately 95 million U.S. adults who qualify.

The 2013 Guidelines for Managing Overweight and Obesity in Adults advocate for high-intensity programs with 14 counselling sessions over 6 months, leading to significant weight loss and improved cardiovascular health.

Efforts to expand access through community-based and digital platforms aim to lower costs and enhance the effectiveness of lifestyle modification programs [4].

However, the effectiveness of these interventions remains a subject of debate, with conflicting evidence reported in the literature.

Furthermore, adherence rates to lifestyle interventions are often low, and the long-term success achieved is moderate at best.

Systematic reviews, which offer a rigorous and transparent methodology for synthesizing existing evidence, have been conducted to evaluate the efficacy of lifestyle interventions for obesity management.

However, many of these reviews have yielded inconclusive results, partly due to the inclusion of various study designs and inadequate consideration of follow-up duration [5].

This review focused on and addressed the research question: “What is the overall effect of lifestyle interventions (diet and physical activity) on weight reduction among adults with obesity, as determined by randomized controlled trials (RCTs)?”

It aims to provide clarity on the efficacy of lifestyle interventions in addressing obesity and to strengthen the evidence base for promoting sustainable healthcare practices.

Objective

This systematic review aims to evaluate and synthesize evidence from randomized controlled trials (RCTs) on lifestyle interventions, including dietary and physical activity modifications, for adults with obesity.

The objective is to determine the overall effect and sustainability of such interventions on weight reduction.

By consolidating high-quality research findings, this review seeks to provide valuable insights for healthcare practitioners, policymakers, and researchers, thereby guiding future intervention strategies and contributing to the broader understanding of effective, evidence-based approaches to obesity management.

Methods

Reporting method

This systematic review with meta-analysis was performed and reported in accordance with the "Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA)" standards [6].

Study design

Systematic Review and Meta-Analysis.

Search strategy and selection criteria

We performed a comprehensive systematic review to capture all published articles from 27th November 2023 to 6th January 2024 in PubMed, Google Scholar, and institute Library e-Resources, in English.

MeSH phrases, free-text words, and alternative words were used to generate the search terms.

After testing acceptable search phrases, the keywords used were “randomized controlled trial,” “obesity,” “weight reduction”, “life style intervention,” and “adults”.

The bibliographies of the collected papers had been further searched for related publications. (Table 1)

Table 1.

Various search strategies according to databases

Database	Search strategy	No. of studies available
Pubmed	(lifestyle intervention) OR (lifestyle modification)) OR (non-pharmacological intervention)) AND (diet)) OR (exercise)) OR (diet)) AND (exercise)) OR (weight loss)) OR (weight reduction)) OR (weight management)) AND (obesity)) OR (obese adults)) AND (randomized controlled trial)) OR (RCT)) OR (TWO ARM RCT) Filters applied: Free full text, Randomized Controlled Trial, in the last 10 years, Adult: 19-44 years, Middle Aged: 45-64 years.	2274
Google scholar	two arm randomized controlled trial weight management through non pharmacological or lifestyle intervention among obese adults intervention no reviews modification "life style" -reviews https://scholar.google.com/scholar?as_q=two+arm+randomized+controlled+trial+weight+management+through+non+pharmacological+or+lifestyle+intervention+among+obeseadults+intervention+no+reviews&as_epq=life+style&as_oq=modification&as_eq=reviews&as_occt=any&as_sauthors=&as_publication=&as_ylo=2012&as_yhi=2023&hl=en&as_sdt=0%2C5	468
Institute e- library	https://jipmerlibrary.ovidds.com/discover/results?q=weight+loss+programs">https://jipmerlibrary.ovidds.com/discover/results?q=weight+loss+programs https://jipmerlibrary.ovidds.com/discover/results?q=(weight+loss+programs)+AND+(lifestyle+intervention+)+AND+(obesity+adults)+AND+(diet+)+AND+exercise+AND+(randomized+controlled+trial)+AND+(one+year+follow+up)&db=COM.DISCOVER.INDEX.GRP">https://jipmerlibrary.ovidds.com/discover/results?q=(weight+loss+programs)+AND+(lifestyle+intervention+)+AND+(obesity+adults)+AND+(diet+)+AND+exercise+AND+(randomized+controlled+trial)+AND+(one+year+follow+up)&db=COM.DISCOVER.INDEX.GRP https://jipmerlibrary.ovidds.com/discover/results?q=obese+adults+AND+lifestyle+modification+AND+standard+care+AND+weight+reduction+AND+12+weeks">https://jipmerlibrary.ovidds.com/discover/results?q=obese+adults+AND+lifestyle+modification+AND+standard+care+AND+weight+reduction+AND+12+weeks	275

Criteria for Study Inclusion and Exclusion

Studies matched the inclusion requirements, such as original article, lifestyle intervention based on nutrition, without or with exercises, and without or with technology aid among individuals aged 18 years and above who are overweight, obese with or without co-morbidity.

Also the study was published in English in the last 10 years (2012‐2023) were included.

Here we included only two arm RCTs as it gives clear intervention allotment in a trial with one primary null-hypothesis.

Despite having registered in PROSPERO to include studies with a minimum follow-up of one year, we are currently unable to obtain sufficient articles.

As a result, we included the original article with a minimum 6-week follow-up.

Studies on children, adolescents, and pregnant women were excluded, as were participants with established cancer, diabetes, cardiovascular disease, or eat-related disorders, known hypercholesterolemia, weight loss surgery, polycystic ovary syndrome, renal failure, or severe lung disease, as well as studies with no control group or no outcome data for the control group.

Other than RCT research designs, interventions other than lifestyle modification (such as medicine or dietary supplements) were excluded.

Study selection

All citations found were exported to Rayyan-AI Powered Tool for Systematic Literature Reviews where duplicates have been deleted.

An independent search was done by two reviewers using computerized databases. Both reviewed all abstracts and titles.

Disagreements about the inclusion of papers were settled by consulting with a third researcher.

We contacted writers in order to obtain full-text publications that are not currently available.

The articles were chosen based on an impartial examination of complete texts to ensure that all the criteria for inclusion and exclusion have been satisfied.

Our search strategy captured 3018 studies in a period of 10 years (2012‐2023); of which, 42 met our inclusion criteria for weight-loss which focused on lifestyle intervention randomized controlled trials with at least 6 weeks follow-up for full article analysis, of those, and 15 were eligible for meta‐analysis.

Figure 1 depicts a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow flowchart for research selection.

Figure 1.

PRISMA flow diagram depicting the process of study identification, screening, eligibility assessment, and inclusion for the systematic review and meta-analysis

Data extraction and quality assessment

Data was retrieved for all review outcome measures.

Author, publication year, country, study methodology, sample size, mean age, participant characteristics, type of intervention to both groups, duration and method of delivery (e.g. traditional (face-to-face) or technological (mobile app/web based, text messages), all data pertaining to mean difference with standard deviation for both groups, as well as other significant information.

We contacted the authors personally via Research Gate while extracting the data for pertinent data not provided in the publications.

Extracted studies were carried out in a number of nations, including Saudi Arabia, Asia, the Czech Republic, the United Kingdom, Malaysia, Beijing, Australia, Germany, Munich, India, and the United States.

The Jadad scale (from 0 to 5) was used to evaluate the methodological quality such as degree of quality of randomization, the use of blinding and participant withdrawals or dropouts [7].

Data synthesis and statistical analysis

A quantitative data synthesis was conducted to get an aggregate figure of the included studies' influence on body weight outcome.

The difference in mean body weight from baseline to end line and its standard deviation were considered to screen studies for outcomes that might be included in meta-analyses.

The data was analysed using STATA version 14.

Inconsistency index I2 values were used to compute heterogeneity, and a funnel plot with visual inspection was used to assess research publication bias [8, 9, 10].

A subgroup meta-analysis was done, stratified by follow-up duration and mode of intervention received by intervention group.

We did not attempt to utilize random effect or fixed-effect analysis because the results were unambiguous and there was little heterogeneity.

Results of systematic review

Obesity and overweight are complex multifactorial conditions with significant health implications.

This systematic review aims to provide a comprehensive analysis of weight reduction interventions, shedding light on their effectiveness, heterogeneity, and potential for publication bias.

The included studies were published between January 2014 and December 2023 and conducted in 15 countries, [11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25] with the majority (n=3) done in the United States [14, 23, 25] (Table 2&3).

Table 2.

Included Studies Characteristics

Author	Country	Year	Age in years Mean (SD)	Mode of intervention Components Providers	Time	IG (N)	CG (N)	Participants’ characteristics	Type of care in CG	Blinding	Type of Care in Intervention-IG
Lin PH	Beijing	2013	38.21 (7.99)	Text-message Diet &PA HC team	6 months	63	60	BMI 24, age 30 50, current use of a mobile phone and interest in losing weight	Control group received a brief advice session	Outcome assessor	Lifestyle intervention group. self-monitor their adherence to these goals via a daily text message
Moss J	UK	2014	NA	Conventional Diet &PA HC team	12 weeks	30	30	Obese adults with continuous positive airway pressure treated obstructive sleep apnea hypopnea syndrome (OSAHS)	Advice-only control group	Not blinded	Supervised exercise sessions, dietary advice, and the promotion of lifestyle behaviour change using cognitive-behavioral techniques
Blackford K	Australia	2016	61 (5.41)	Home based Diet &PA HC team	6-month	151	161	Participants with MetS aged 50 to 69 years	Waitlisted to receive the programm after post-test data collection	Not blinded	The intervention group received printed and online program materials and motivational support
Jamal SN	Malaysia	2016	40.5 (9.3)	Conventional Diet &PA HC team	36 weeks	97	97	Overweight and obese (BMI>27.5kg/m2) employees	Dietary counselling once in 12 weeks	Not blinded	Group Support Lifestyle Modification
Alghamdi RQ e	Saudi and Arab	2017	36.15 (9.99)	Conventional Diet &PA HC team	12 weeks	70	70	Age>20 years, BMI (≥30 kg/m2) ≥ 25	Education-only active comparator (AC)	Investigator	Intensive lifestyle intervention program
Einarsson S	Sweden, Denmark and Iceland	2017	31.6 (4.2)	Conventional low calorie liquid formula diet	18 weeks	152	153	Women under 38 years of age planning IVF, and having a BMI≥30 and	IVF only	Outcome assessor &statistician	Low calorie liquid formula diet(LCD) of 880 kcal/day and thereafter weight stabilization
Das SK	America	2021	40.75 (10.75)	Conventional Diet &PA HC team	12 months	121	117	Adult (≥18 y old), BMI (in kg/m2) ≥25	modified Diabetes Prevention Program (m-DPP)	Outcome assessor	Healthy Weight for Living (HWL)
Bender MS	United States	2017	57.6 (9.8)	mobile app Diet &PA HC team	24 weeks	22	23	Key inclusion criteria were self-identified Filipino; ≥18 years; BMI >23kg/m2 for Asians; physician diagnosis of T2D (non-insulin dependent); own a smartphone, tablet, or laptop with Internet access; and English language proficient	The waitlist control received the PilAm Go4Health in phase 2	Statistician	PilAm Go4 Health intervention (phase 1) with an active waitlist control and 3-month follow-up (phase 2).
AHN JS	Republic of Korea	2020	26.0 (4.8)	mobile app Diet &PA HC team	6 weeks	25	25	18-40 years of age, BMI ≥23kg/m, willingness for weight loss, and smart phone ownership	The paper-based diary group was instructed to record foods or supplements that they consumed using a self-recorded diary	Not blinded	The smartphone app group recorded foods and dietary supplements that they consumed and received immediate dietary feedback us ing Well-D, and dietary self-monitoring app
Lim SL	Singapore	2020	46.5 (10.6)	mobile app Diet &PA HC team	6 months	108	108	Above 21 years with NAFLD	General care	Investigator blinding	Mobile App Intervention Group
Vaz CL	USA	2021	43.25 (13.1)	web based Diet &PA HC team	6 months	13	15	Body mass index 25-42kg/m2,withsmartphones and sedentary jobs	Await ‐listed control group that received only weight‐management visits	Not blinded	Conventional out patient weight‐management visits every three months
Brame J	Austria	2022	50.0 (10.8)	web based Diet &PA HC team	12 weeks	39	53	subjects with overweight and obesity (50.0±10.8 years, 76.1% females, 30.5 ±2.1kg/m2)	Non -interactive web-based weight loss program	Outcome assessor	Interactive web-based weight loss program
Moravcova K	Germany	2022	43.3 (9.5)	mobile app Diet &PA HC team	3 months	33	25	Obese patients (defined as BMI over 30kg/m2) older than 18 years	The control group (CG) received a series of in-person consultations	Not blinded	Used Vitadio
Gemesi K	Munich	2023	46.8 (11.0)	mobile app Diet &PA HC team	24 weeks	59	54	Age between 18 and 70 years, BMI between 30.0 and 40.0kg/m2, no severe diseases (e.g. diagnosed diabetes mellitus, cardiovascular disease, and cancer), ownership of a smartphone	Received the app-based intervention	Not blinded	Received an app-based multimodal weight loss program
V Krishnasamy	India	2024	38.04 (7.53)	Home base Diet &PA HC team	12 weeks	44	44	Adults aged 18-50 years with BMI ≥25kg/m2 with no severe diseases	Education and learning materials distributed at the end	Outcome assessor	Nurse-led intervention on diet, physical activity-community based.
NOTE: NA- not available. HC team- health care team

Table 3.

Included studies weight outcome measures

Author	Country	Year	IG (N)	IG mean	IG (SD)	CG (N)	CG mean	CG (SD)
Lin PH	Beijing	2014	63	-1.6	2.22	60	0.24	2.15
Moss J	UK	2014	30	0.2	-0.9	30	2.3	-0.1
Blackford K	Australia	2016	151	-0.7	1.1	161	1.1	0.1
Jamal SN	Malaysia	2016	97	-1.52	0.36	97	-0.09	0.19
Alghamdi RQ	Saudi and Arab	2017	70	-5.58	5.6	70	-2.8	4.96
Einarsson S	Sweden, Denmark and Iceland	2017	152	−9.44	6.57	153	1.19	1.95
Das SK	America	2021	121	−7.46	0.85	117	−7.32	0.87
Bender MS	United States	2017	22	-1.8	0.2	23	-2.4	1.2
AHN JS	Republic of Korea	2020	25	-0.4	-1.6	25	-1.4	-2.7
Lim SL	Singapore	2020	108	-4.1	3.8	108	-0.7	2.8
Vaz CL	USA	2021	13	−7.16	1.78	15	−3.00	1.05
Brame J	Austria	2022	39	-3.6	0.4	53	-1.2	0.3
Moravcova K	Germany	2022	33	7.1	6.5	25	4.8	5.8
Gemesi K	Munich	2023	59	−3.3	4.8	54	−2.1	3.3
V Krishnasamy	India	2024	44	-2.6	0.9	44	0.38	0.14

IG (N)-intervention group sample size

IG mean-intervention group mean

IG (SD)-intervention group standard deviation

CG (N)-control group sample size

CG mean-control group mean

CG (SD)-control group standard deviation

Characteristics of studies

A systematic search strategy was meticulously implemented to identify relevant studies focusing on weight reduction interventions in individuals with obesity and associated comorbidities.

The inclusion criteria encompassed randomized controlled trials, cohort studies, and intervention trials across various age groups and demographic profiles.

Data synthesis and analysis were conducted using established methodologies, with particular emphasis on the impact of interventions on weight reduction outcomes across different health conditions.

Fifteen studies were included in the review, collectively investigating weight reduction interventions in individuals with various obesity-related comorbidities, including metabolic syndrome, infertility, OSAHS treated with positive airway pressure, type 2 diabetes, NAFLD, and sedentary behavior.

Notably, the majority of the included RCTs enrolled participants of both male and female genders, with one trial specifically focusing on females awaiting in vitro fertility treatment.

This diverse representation ensures the generalizability of the findings across different populations [20, 21, 22, 23, 24, 25].

Eight of the included studies utilized web or mobile-based lifestyle interventions as a means of delivering weight reduction interventions.

These digital platforms offer convenient and accessible avenues for individuals to access support, guidance, and resources for managing their weight.

Conversely, traditional face-to-face interactions were employed in seven studies, highlighting the continued relevance of in-person counseling and support in weight management programs.

Across all studies, the lifestyle interventions encompassed a comprehensive approach, integrating dietary modifications, structured exercise regimens, and self-monitoring practices.

This holistic approach addresses multiple facets of weight management, fostering sustainable behavior change and long-term success.

Importantly, the interventions were facilitated through collaboration among healthcare professionals, including dietitians or nutritionists, doctors, nurse practitioners, experts in psychology, physical instructors, or trainees.

This multidisciplinary approach ensures the provision of comprehensive care tailored to individual needs and preferences.

In four of the included studies, the control group received only education or advice regarding weight management [11, 12, 13, 20].

This minimalist approach serves as a baseline comparison to assess the efficacy of more intensive interventions.

Conversely, one of the remaining three studies incorporated a paper-pencil diary as part of the intervention and follow-up process.

This self-monitoring tool provides participants with a tangible means of tracking their progress and adherence to dietary and exercise guidelines.

The interventions employed in the studies encompassed a variety of modalities, including non-interactive web-based guidance, app-based interventions, and series of in-person consultations.

Participants in one study received non-interactive web-based guidance, leveraging digital platforms to deliver structured weight management support and resources.

Another study utilized an app-based intervention, providing participants with interactive tools and features to facilitate self-monitoring, goal setting, and behavior modification.

Additionally, a series of in-person consultations were conducted in conjunction with dietary and exercise counseling to provide personalized support and guidance to participants [15, 16, 17, 18].

One of the included studies provided dietary counseling at 12 weeks, with a follow-up period of 36 weeks [14].

This extended duration of counseling may have contributed to sustained behavior change and improved weight management outcomes.

Several studies provided the control group with general care [14, 15, 16, 17, 18, 19, 22, 23, 24] or waitlisted for intervention following post-test data collection [21, 23, 25].

This approach serves as a comparator to assess the efficacy of the intervention under investigation, highlighting the importance of controlling for confounding variables.

Four studies were blinded for outcome assessors, [11, 14] minimizing the risk of bias in outcome assessment.

Similarly, two studies were blinded for investigators, reducing the potential for biased intervention delivery [15, 24].

One study was blinded for the statistician, ensuring unbiased data analysis, [23] while another study was blinded for both investigators and the statistician, further enhancing the credibility of the findings [22, 23].

However, many studies were non-blinded, citing the nature of the lifestyle intervention as a barrier to blinding [12, 15, 17, 18, 20, 21, 25].

This limitation underscores the challenges inherent in blinding participants and healthcare providers in lifestyle interventions.

Risk of bias

Most studies also revealed a high risk of bias because no blinding of participants or researchers was feasible owing to the nature and requirements of these trials, hence a large number of studies were open labeled.

The methodological quality of the included studies was assessed independently by two reviewers using the Jadad scale.

The Jadad scale assigns scores based on randomization (0-2 points), blinding (0-2 points), and withdrawals/dropouts (0-1 point), with a maximum total score of 5.

Studies with a Jadad score of >3 were considered to have higher methodological quality, indicating robust methodology with minimal risk of bias (Table 4)

Table 4.

Quality assessment of included RCTs using JADAD Scale

Study	Country	Year	*Described as randomized	*Described as double blind	*Description of withdrawals	** Randomization method described and appropriate	** Double blinding method described and appropriate	Score
Lin PH	Beijing	2014	1	1	1	1	0	4
Moss J	UK	2014	1	0	1	1	0	3
Blackford K	Australia	2016	1	0	1	1	0	3
Jamal SN	Malaysia	2016	1	0	1	1	0	3
Alghamdi RQ	Saudi and Arab	2017	1	1	1	1	0	4
Einarsson S	Sweden, Denmark and Iceland	2017	1	1	1	1	1	5
Das SK	America	2021	1	1	1	1	0	4
Bender MS	United States	2017	1	1	1	1	0	4
AHN JS	Republic of Korea	2020	1	0	1	1	0	3
Lim SL	Singapore	2020	1	1	1	1	0	4
Vaz CL	USA	2021	1	0	1	1	0	3
Brame J	Austria	2022	1	1	1	1	0	4
Moravcova K	Germany	2022	1	0	1	1	0	3
Gemesi K	Munich	2023	1	0	1	1	0	3
V Krishnasamy	India	2024	1	1	1	1	0	4

Note:

*A study receives a score of 1 for “yes” and 0 for “no”

**A study receives a score of 0 if no description is given, 1 if the method is described and appropriate, and -1 if the method is described but inappropriate.

#The word “double blind” was not used by the authors. However, according to the description of the blinding of the investigator, investigator site staff, and participants, one point was given for “described as double blind”

Results of Meta-analysis

A meticulous search strategy was employed to identify relevant studies from electronic databases, encompassing randomized controlled trials and intervention studies targeting weight reduction.

Data extraction and synthesis were conducted using rigorous methodology, with particular attention to sample characteristics, intervention outcomes, and statistical analysis.

The selected studies exhibited a wide range of sample sizes, reflecting the diverse population demographics.

Effect of randomized controlled trials on life style intervention in obese adults

The inclusion criteria encompassed individuals aged 18 to 70 years, with the average age calculated at 42.8 years.

This diversity underscores the broad applicability of the findings across different age groups and demographic profiles.

Within the intervention group, a substantial mean difference in weight reduction was observed, with a mean decrease of-2.79±3.93kg.

In contrast, the control group exhibited a comparatively lower mean difference in weight loss (-0.73±2.8kg), highlighting the efficacy of the interventions in promoting significant weight reduction.

Meta-analysis of the aggregated data revealed a mean difference in weight decrease of -1.78 (95% CI -2.28, -1.27), providing robust evidence of the effectiveness of the interventions across diverse study populations.

Notably, the analysis demonstrated non-significant heterogeneity among the included studies, with an I2 statistic of 0.0% and a p-value of 0.455 (Figure 2).

Figure 2.

Forest plot showing the mean difference in weight reduction (kg) with standard deviations among adults with obesity receiving lifestyle interventions compared with control groups

This suggests consistency in weight reduction outcomes across various intervention modalities, enhancing the reliability and generalizability of the findings.

Furthermore, the symmetrical display of the funnel plot for total effect estimates suggests a minimal probability of publication bias, reinforcing the credibility and validity of the observed effect sizes.

Relationship between intervention characteristics and weight loss outcomes in randomized controlled trials

A meta-analysis was performed to compare the effectiveness of conventional versus technological-based intervention delivery methods.

The analysis revealed a mean difference in weight loss of -1.66 kg (95% CI -2.28, -1.04) with conventional methods and -2.00kg (95% CI -2.26, -1.14) with technological-based interventions.

Interestingly, both intervention modalities demonstrated non-significant heterogeneity, with I2 values of 0.0% and p-values of 0.427, suggesting consistency in weight reduction outcomes across studies (Figure 3).

Figure 3.

Forest plot illustrating the mean difference and standard deviation in weight reduction based on the mode of lifestyle intervention delivery

The symmetrical appearance of the funnel plot further supports the robustness of the findings, suggesting a minimal probability of publication bias.

This indicates that the observed effect sizes are unlikely to be influenced by selective reporting or publication practices.

Both approaches demonstrate significant reductions in body weight, with minimal heterogeneity and evidence of publication bias, enhancing the credibility and generalizability of the findings.

Studies with a follow-up period of six months or less exhibited non-substantial heterogeneity (I2=0.0%; p=0.754) and demonstrated an average weight difference of -2.41 kg (95% CI -3.18, -1.65).

This suggests that short-term interventions are associated with significant and clinically meaningful weight reduction outcomes.

Conversely, studies with follow-up durations exceeding six months to 12 months also showed non-substantial heterogeneity (I2=0.0%; p=0.455) but exhibited a slightly lower average weight difference of -1.29kg (95% CI -1.96, -0.62) (Figure 4).

Figure 4.

Forest plot depicting the mean difference and standard deviation in weight reduction according to the duration of lifestyle interventions

Despite the decrease in average weight difference, these longer-term interventions still resulted in significant weight reduction.

The symmetrical appearance of the funnel plot further corroborates the robustness of the findings, suggesting a minimal probability of publication bias.

This indicates that the observed effect sizes are unlikely to be influenced by selective reporting or publication practices, enhancing the credibility of the results.

Discussion

Obesity can cause a variety of serious and sometimes fatal illnesses and also have an impact on quality of lifestyle and contribute to psychological issues.

Effective weight reduction strategies are pivotal in combating the global burden of obesity.

This systematic review investigates the impact of lifestyle interventions on weight reduction outcomes, exploring the nuances of intervention duration and delivery mechanisms.

A rigorous search strategy was employed to identify relevant randomized controlled trials (RCTs) investigating lifestyle interventions for weight reduction.

Methodological quality assessment was conducted, and data synthesis was performed to elucidate key findings and trends.

Fifteen RCTs were included in the review, comprising a total of 2062 individuals.

The average age of participants was 42.8 years, with an age range spanning from 18 to 70 years.

This diverse sample reflects the broad applicability of lifestyle interventions across different age groups.

Across all investigations, a total impact size of -1.78 kg (-2.2%, -1.27%) was recorded, indicating a statistically significant reduction in body weight following lifestyle interventions.

These findings underscore the efficacy of lifestyle interventions in promoting weight reduction.

Analysis revealed that the duration of the research influenced the effectiveness of lifestyle interventions on weight reduction.

Longer-duration studies tended to yield more pronounced effects on weight loss outcomes, highlighting the importance of sustained intervention efforts over time.

Furthermore, the mechanism of delivery of the intervention also played a significant role in determining its effectiveness.

Various delivery mechanisms, such as face-to-face counseling, web-based interventions, and mobile applications, demonstrated positive effects on weight reduction outcomes.

The elaborate analysis of lifestyle interventions on weight reduction highlights their significant impact on promoting weight loss across diverse populations.

Factors such as intervention duration and delivery mechanisms contribute to the variability in intervention effectiveness, underscoring the need for tailored and multifaceted approaches to weight management.

The consistent findings of efficacy, coupled with the absence of significant heterogeneity and publication bias, highlight the robustness and reliability of the evidence base supporting these interventions.

Self-tracking, setting objectives, encouragement, and behavioral modification are recognized as fundamental behavioral techniques integral to behavioral weight-loss treatment.

These techniques are consistently included in weight-loss regimens across various interventions.

Additionally, other useful behavioral strategies such as problem resolution, preventing weight rebound, and stress management are highlighted as important components of effective weight reduction interventions.

These strategies aim to address common challenges and barriers to successful weight management.

Social support from partners, family members, friends, and other individuals has emerged as a crucial factor in promoting successful weight reduction.

Studies have shown that social support can enhance adherence to treatment protocols, provide motivation, and foster a supportive environment conducive to behavior change.

The inclusion of social support components in weight-loss interventions underscores the importance of leveraging interpersonal relationships as a resource for achieving weight management goals.

The bulk of publications included in this review focused on behavioral interventions in weight loss strategies.

This emphasis reflects the growing recognition of the central role that behavioral techniques play in the success of weight reduction efforts and the increasing interest in developing effective behavioral interventions [26].

The findings of this study are supported by the recommendations outlined in the American Dietetic Association's Adult Weight Management An Evidence-Based Nutrition Practice Guideline.

According to these guidelines, weight reduction and maintenance therapy should be guided by a comprehensive weight-management strategy that incorporates dietary modifications, increased physical activity, and behavioral modification.

The emphasis on a holistic approach to weight management underscores the importance of addressing multiple facets of behavior, lifestyle, and nutrition to achieve sustainable weight loss and maintenance [27].

Our analysis supports the effectiveness of nutritional and dietary specialists as counseling interventionists in weight reduction programs.

These specialists play a crucial role in providing personalized dietary guidance, addressing nutritional needs, and promoting behavior change to facilitate weight loss.

The discrepancy in outcomes observed across studies may be attributed to variations in the quality of face-to-face interactions or the utilization of technology in certain lifestyle programs.

Effective communication and engagement between counselors and participants are key factors influencing intervention success.

The included studies exhibited significant variability in sample size and intervention length, reflecting the diversity of study designs and methodologies.

This variability may contribute to heterogeneity in outcomes, as larger sample sizes and longer intervention durations may yield more robust and reliable results.

Furthermore, significant variation was observed in the forms of intervention and follow-up adopted, ranging from face-to-face counseling sessions to technology-based interventions.

These differences in intervention modalities may influence adherence, engagement, and ultimately, weight loss outcomes.

Our investigation suggests that technology-based interventions may have a greater effect on weight loss compared to conventional interventions.

The integration of technology, such as mobile applications, web platforms, and wearable devices, offers novel opportunities for enhancing engagement, providing real-time feedback, and facilitating behavior change.

The majority of smartphone apps utilized in weight reduction interventions focused on diet and physical activity tracking, providing users with tools to monitor their routines and progress.

While these apps offer significant benefits in promoting adherence to weight loss goals, they may pose challenges for certain populations, particularly the elderly, due to technological complexities and usability issues.

Telephone calls and text messages are perceived as faster communication platforms compared to smartphone apps.

These modes of communication offer a direct and efficient means of exchanging information, making them particularly suitable for delivering timely support and feedback to individuals participating in weight reduction programs.

Despite the perceived advantages of telephone calls and text messages, smartphone apps remain one of the most promising platforms for weight reduction interventions due to their versatility and additional capabilities.

These apps offer features such as real-time tracking, personalized feedback, and social support networks, enhancing user engagement and motivation.

The efficacy of weight reduction interventions delivered through different modalities is influenced by users' level of awareness and education.

User-friendly interfaces and accessible features are essential for ensuring equal effectiveness across diverse user populations.

The length of intervention and follow-up periods varied significantly across studies included in the review, ranging from six weeks to several months.

This variability may contribute to differences in weight loss outcomes, highlighting the importance of standardized intervention durations and follow-up protocols.

The mean difference in weight loss was 2.41kg for studies with a follow-up period of six months or less, compared to 1.29kg for trials with a follow-up period between six and twelve months.

This suggests that initial weight loss is typically faster than subsequent losses, highlighting the importance of understanding the dynamics of weight reduction over time.

Health care professionals and participants often express disappointment when weight loss plateaus after approximately six months, despite continued adherence to reduced calorie intake or further caloric restriction in some trials.

This phenomenon underscores the need to shift the emphasis of weight management plans from focusing solely on weight loss to incorporating strategies for ongoing weight loss maintenance.

Given that weight loss tends to plateau after the initial six months, interventions should prioritize sustainable lifestyle changes, behaviour modification strategies, and support mechanisms to facilitate long-term weight maintenance [5].

To prevent weight regain and promote long-term weight maintenance, individuals must adhere to a low-energy diet and engage in regular physical activity.

These lifestyle modifications are fundamental components of effective weight management strategies and are associated with numerous health benefits beyond weight loss.

The American College of Sports Medicine recommends specific guidelines for physical activity to achieve clinically significant weight loss and maintain weight after weight loss.

For clinically significant weight loss, individuals are advised to engage in 250-420 minutes of moderate-intensity physical activity per week.

For weight maintenance following weight loss, the recommended range is 200-300 minutes per week [28].

Consistency emerges as a key determinant of successful weight loss across different timeframes.

Regardless of the duration of intervention or the specific approach employed, consistency in adherence to lifestyle modifications is crucial for achieving and maintaining weight loss outcomes.

Prioritizing patients' needs and assessing their present state and challenges are essential steps in designing effective weight reduction interventions.

Tailoring interventions to individual circumstances and preferences enhances engagement, adherence, and ultimately, the success of weight management efforts.

Our findings suggest that various forms of lifestyle modifications, including dietary changes, physical activity interventions, behavioral strategies, and support mechanisms, can be highly effective in promoting weight loss.

The diversity of interventions underscores the importance of adopting a multifaceted approach to weight management.

Limitations

This systematic review aimed to assess the effectiveness of lifestyle interventions for weight reduction in obese adults without chronic severe co-morbidities.

Here, we provide a detailed analysis of the limitations encountered during the review process and offer insights into areas for future research and improvement.

The review was limited to obese adults without chronic severe co-morbidities, which may have restricted the generalizability of the findings to broader populations with diverse health conditions.

Future reviews may consider expanding inclusion criteria to encompass a wider range of participants and co-morbidities.

Due to the inclusion criteria specifying trials with only two arms (complete lifestyle intervention or comparator), the review was unable to infer the effect of individual components of lifestyle interventions on weight loss.

This limitation highlights the need for more nuanced analyses in future reviews to elucidate the specific contributions of different intervention components.

Some studies included in the review had smaller sample sizes, poor blinding, and shorter trial durations, which may have impacted the ability to establish the long-term impact of lifestyle treatments on weight reduction outcomes.

Future studies should aim to address these methodological limitations to provide more robust evidence.

The review did not include statistics on the effects of lifestyle changes on cost-effectiveness or customer satisfaction levels, which are important considerations in evaluating the overall impact of interventions.

Future research should aim to incorporate these outcome measures to provide a more comprehensive assessment of the effectiveness and acceptability of lifestyle interventions.

Implications

Further research into the interconnections between various intervention strategies and their components is recommended.

Understanding how different components of interventions interact and contribute to weight reduction outcomes can inform the development of more effective and tailored interventions.

Future studies should investigate patients' ideas and attitudes regarding the design components and physical features of various interventions, including face-to-face interactions, mobile applications, text messages, and phone calls.

Assessing the acceptability and utility factors of different intervention modalities can help tailor interventions better to meet patients' needs and preferences.

The cost-effectiveness of weight reduction interventions should be assessed to determine their impact and feasibility in clinical or community practice.

Understanding the economic implications of different intervention approaches can inform resource allocation decisions and support the integration of effective interventions into healthcare systems.

Lifestyle treatments for weight reduction may be prioritized in National Health Programs, given their potential impact on public health outcomes.

Evaluating the cost-effectiveness of these interventions at the national level can provide policymakers with valuable insights into the allocation of resources and the implementation of evidence-based interventions on a larger scale.

Conclusions

In conclusion, this systematic review has shed light on the impact of lifestyle modifications on weight loss in obese individuals.

While the evidence presented indicates that lifestyle interventions can be considered effective methods for weight reduction among obese patients, it is important to acknowledge the limitations and inconsistencies within the existing body of research.

The findings suggest that there is a need for more extensive and innovative research into various lifestyle intervention strategies.

Methodological differences across studies, variations in intervention protocols, and inconsistent outcome measures contribute to the challenge of drawing firm conclusions.

Therefore, researchers are encouraged to prioritize openness in reporting interventions, taking into account contextual factors, aims, delivery modes, and effect mechanisms for optimal data interpretation.

Furthermore, there is a clear call for more inventive approaches to studying lifestyle interventions.

Tailoring interventions to individual needs, incorporating technology-based solutions, and exploring novel intervention components are avenues that warrant further investigation.

By embracing creativity and rigor in study design, researchers can contribute to a deeper understanding of effective weight reduction strategies.

In summary, while lifestyle interventions show promise as effective methods for weight loss among obese individuals, there is a pressing need for more robust and comprehensive research.

By addressing the limitations highlighted in this review and fostering a culture of openness and innovation, we can advance the field of weight reduction interventions and ultimately improve outcomes for individuals struggling with obesity.

Conflict of interests

The authors declare no competing interests.