Table 1.

Summary of Included Studies on Dietary Interventions in the Workplace.

Author, Year	Country, MetS Clinical Criteria	Population Studied (N, M to F Ratio, Age, Occupation)	FUP	Health Status Inclusion Criteria	Intervention	Outcome Variables	Results	Conclusions
Woo et al., 2020 [27]	South Korea, NI	N: 68 (IG1 23; IG2 19; CG 26) M/F: NI Age range: 25–60 years Occupation: hospital workers	12 weeks	2 risk factors for MetS or 1 risk factor for CVD	Social Network Service-Based Lifestyle-Modification Programme. IG1: education/counselling about regular physical activity; doctor consultation; nutritional goals. IG2: only educational information. CG: no intervention.	CVD risk factors: BP, WC, BMI, TG, TC, HDL-c and LDL-c. Health beliefs, health promotion behaviours and self-efficacy. Data collected at baseline, 6 weeks and 12 weeks in all 3 groups.	Week 6: IG1 showed significant decrease in WC, BMI, TC, LDL-c, health promotion behaviours and self-efficacy, but not significantly greater than in IG2 or CG. Week 12: IG1 showed significant decrease in WC, BMI, TC, LDL-c. Self-efficacy and health promotion behaviours improved to a greater degree in IG1 than in IG2 and CG.	Programme improved self-efficacy and health behaviour, improving CVD risk factors
Kempf et al., 2019 [28]	Germany, NI	N: 104 (IG 34; CG1 34; CG2 36) M/F: 84/16 Mean age: 50 years Occupation: employees of medical company Boehringer Ingelheim	36 months	Overweight (BMI ≥ 25 kg/m2 and/or WC > 94 cm for men or >80 cm for women).	Telemedical coaching focused on controlled weight loss with or without telemonitoring. IG: Telemedical coaching + telemonitoring (scales and pedometer) + weekly then monthly care calls over 12 months. CG1: scales and pedometer from baseline CG2: short coaching phase (monthsmonths 6–9) + scales and pedometer from mth 6.	1. Weight loss after 12 months in all 3 groups 2. Difference in weight loss after 6 months (IG vs. C1 and IG vs. C2). 3. BMI, WC, SBP/DBP, TG, TC, HDL-c, LDL-c, HbA1C, FBG, CRP, eating behaviour, PA. Data collected at 3, 6, 9, 12 and 36 months.	Significant reduction in BMI, SBP/DBP and eating behaviour in all groups. Weight loss after 12 months: IG vs. CG1: −3.6 kg (−7.4; −0.1) (p = 0.047); IG vs. C2: −4.2 kg (−7.9; −0.5) (p = 0.026) in per-protocol analysis. ≥5%weight loss at 12 months: IG: 63% (p = 0.037); CG1: 33%; CG2: 31% in per-protocol analysis. At 36 months: weight loss at 12 months was maintained until 36 months. All 3 groups significantly reduced weight (IG: −8.4 [95% CI −11.3; −5.4] kg; CG1: −4.0 [95% CI −6.6; −1.8] kg; CG2: −3.3 [95% CI −5.8; −0.8] kg). No difference between groups in per-protocol or intention to treat analyses after 3 years	Improvements in SBP, anthropometric measurements and eating behaviour indicate that telemedical coaching with telemonitoring can help to prevent weight gain and improve health.
Shrivastava et al., 2017 [29]	India, NCEP-ATP-III [35]	N: 598 M/F: 87.9%/12.1% Mean age: IG 35.8 years (SD 7.6); CG 39.0 yearsyears (SD 8.7) Occupation: Employees at 4 corporate worksites (public and private)	6 months	Overweight (BMI ≥ 23 kg/m2)	Multicomponent intervention to improve knowledge, attitude and health lifestyle, focused on healthy living, diet and physical activity. IG: 2 sessions/2 weeks on healthy living, diet, and PA + 2 PA training sessions + stress management sessions. CG: 2 general health talks in 6 months.	1. FBG, TC, HDL-c, LDL-c, TG. 2. Anthropometric measurements (WC, BMI, skinfold). 3. Other behavioural risk factors (tobacco and alcohol), dietary intake/food frequency, PA pattern.	IG achieved significant decrease in weight, BMI, WC, waist to hip ratio, skinfold (biceps, triceps, subscapular, suprailiac), FBG, TG; increase in HDL-c In CG, no significant difference in mean values except FBG and 3 skinfolds (biceps, triceps, subscapular). Weight loss in 12% of IG versus 4% of CG. (12.51 ± 10.38 cm vs. 3.50 ± 8.18 cm reduction in skinfold measurements). Greater conversion from sedentary to more active lifestyle in IG versus CG (67% to 55% vs. 69% to 65%). Lower calorie intake and fat consumption. More individuals in IG than in CG reduced number of risk factors for MetS.	Intervention achieved reduction in weight, subcutaneous fat and cardiometabolic risk factors after 6 months. The results could encourage other worksites in India to implement similar multicomponent interventions.
Proeschold-Bell et al., 2017 [30]	USA, IDF [36]	N: 1114 (IG1 395; IG2 283; IG3 436) M/F: 69.3%/30.7% Mean age: 51.9years (SD 10.0) Occupation: United Methodist clergy	24 months	No health status inclusion criteria	IG1: “Immediate intervention” and IG2: “1 year waitlist”: Personal goal setting + 3 workshops delivering stress management and theological content supporting healthy behaviours + 10–weeks online weight-loss program + small grant. IG3 “2-year waitlist: online stress management + journaling + exercises”.	1. MetS prevalence 2. Prevalence of depression, mean stress score, mean weight. Data collected at 0, 12, 18 and 24 months	Initial MetS prevalence: 50.9% Change in MetS prevalence in IG1: 49.5% to 42.9%; in IG2: 49.8% to 46.1%; in IG3: 49.6% to 45.1%. After 1 yr: 14% MetS prevalence (PR 0.86, 95% CI 0.79; 0.94, p < 0.001). After 2 years: −12% MetS prevalence sustained. Prevalence of components at baseline: central obesity 81.2%, low HDL 57.4%, hypertension 52.6%, high TG 50.9%, abnormal glucose regulation 13.7%. Beneficial effect at 24-months for the 3 most prevalent components Weight loss at 24 months: −3.4 kg for IG1; −4.4 kg for IG2; −1.7 kg for IG3. Depression and stress: no change in depression, gradual decrease in stress in all cohorts.	Spirited Life intervention improved MetS, central obesity, HDL, and BP over 24 months in US Christian Clergy. These findings support long-term behavioural change interventions.
Steinberg et al., 2015 [31]	USA NCEP-ATP-III [35]	N: 2835 (IG 1890; CG 945) M/F: 17%/83% Mean age: 46.53 years Occupation: Aetna employees who had previously participated in MetS biometric screening	12 months	≥2 MetS risk factors, one of which had to be WC	Personalised lifestyle-focused wellness programme. Contact with coaches and client care managers to achieve a healthier weight; focus on nutrition, PA, and behavioural well-being. Genetic profile for 3 genes associated with obesity, appetite and compulsory behaviour. IG1: given information about MetS results + invited to the program. IG2: MetS results + invited to the program + specific prediction of 12-mth future probability of MetS CG: given MetS results but not invited to program.	1. WC, TG, HDL-c, BP, FBG 2. Medical cost per employee-month during 12 months.	WC: greater reduction in IG2 vs. CG (−1.06 inches vs. −0.48 inches, p = 0.02). TG level: greater decrease in IG participants vs. CG (−18,47 mg/dL vs. −2.64 mg/dL, [p = 0.01]) Weight loss: 76% of IG participants lost weight; average weight loss 4.5 kg from baseline (p < 0.001). HDL-c: increase in IG1/IG2 vs. CG. Only IG2 showed significant increase (2.81 mg/dL vs. 1.44 mg/dL, p = 0.02). Total health care cost: lower in IG1/IG2 vs. CG ($312 vs. $434, p < 0.02).	A clinically targeted, personalised wellness program can significantly improve commitment and clinical outcomes related to MetS risk, as well as reducing costs, within just 1 year.
Kramer et al., 2015 [32]	USA NCEP-ATP-III [35]	N: 89 (IG 60; CG 29) M/F: 40/49 Mean age: 52.3 years (range 34–70) Occupation: Employees of Bayer Corporation	12 months	BMI ≥ 24 kg/m2 and evidence of prediabetes.	Lifestyle intervention to achieve and maintain 7% weight loss and to safely and progressively increase to 150 min/wk of moderate physical activity (e.g., brisk walking). IG: immediate intervention CG: delayed intervention (6 months after enrolment) All participants had weekly sessions for 12 weeks (face-to-face or DVD) and monthly meetings for 1 year. All participants were weighed at each in-person meeting and received handouts, pedometer, fat/calorie counter and exercise bands.	1. Change in weight at 6 months vs. baseline 2. BMI, BP, lipid profile, FBG, WC, HbA1c and PA. Data collected at baseline, 6, 12 and 18 months	Greater weight loss in IG vs. CG at 6 months (5.1% vs. 1%) as well as improved WC, HbA1, SBP/DBP, BMI and physical activity time. TG level decreased in IG but not in CG. Nonsignificant difference in TG decrease between groups. Higher proportion of IG achieved at least 5% or 7% weight loss vs. CG (45% vs. 7%, p = 0.0005, and 29% vs. 4%, p = 0.007). Nonsignificant difference in increase in weekly PA between IG and CG (75 min, IQR 30 to 126 vs. 40 min, IQR 0 to 112.5; p = 0.17). Increased HDL at 6 months in men and decrease in women. At 6 months (IG and CG): decreased weight (p < 0.001), HbA1c, SBP/DBP, WC, BMI; and increased PA. At 12 months (IG and CG): decreased TG, DBP/SBP, BMI, WC and HbA1c. At 18 months (IG and CG): decreased weight and WC; increased PA of 25 min/week with baseline (p = 0.04).	This intervention was effective in reducing weight and other risk factors for diabetes and CVD in this worksite setting
Puhkala et al., 2015 [33]	Finland, IDF [36]	N: 113 (IG 55; CG 58) M/F: NI Mean age: IG 47.6 years (SD 7.9) CG: 46.5 years (SD 8.6) Occupation: Long-distance bus and truck drivers.	24 months	WC ≥ 100 cm	Individual lifestyle counselling programme focused on improving nutrition, physical activity and sleep, to reduce body weight and MetS risk factors based on participants’ preferences, abilities and experience. IG: 12 months of counselling on diet, physical activity and sleep (6 individual 1-hr sessions and 7 30-min phone calls). Daily dietary, physical activity and sleep goals. CG: 3 months of counselling after 12 months (2 face-to-face sessions + 3 phone calls)	Weight, WC, glucose, TC, HDL, TG Questionnaire on health status and working conditions. Z-score to evaluate each MetS risk factor. Data collected at baseline, 12 months and 24 months.	Mean body weight change at 12 months: −3.4 kg (p = 0.001, range −26.1–9.9) kg in IG vs. +0.7 kg (p = 0.214, range −9.5–12.5) kg in CG. Net difference −4.0 kg (95% CI −6.2; −1.9) Weight loss at 12 months: 13% of IG lost ≥10% of initial body weight and 13% lost 5−9.9%. MetS prevalence at 12 months vs. baseline: 62% vs. 80% in IG and 60% vs. 62% in CG% (p = 0.34). Greater reduction in Z-score in IG vs. CG. MetS prevalence at 24 months: 60% in IG and 51% in CG. Non-significant difference between groups. Other results at 12 months: in IG, significant decrease in glucose and DBP; significant increase in HDL. Nonsignificant differences in LDL, TG, SBP. Z-score lower in IG.	The study showed clinically meaningful decreases in body weight and cardiometabolic risk factors after 12 months of counselling followed by 12 months of follow-up. Weight reduction and some improvement in cardiometabolic risk factors among long-distance truck and bus drivers is possible through lifestyle counselling, despite challenging working conditions.
Inoue et al., 2014 [34]	Japan NCEP-ATP-III [35]	N: 35 (IG 28; CG 7) M/F: 35/0 Mean age: 47.2 years (SD 7.9). Occupation: male office workers in the city hall	3 months	None partake in daily exercise	Japanese-style healthy lunch menu providing balanced nutrition and sufficient vegetables during 3 months (600–650 kcal, fat < 18 g, cholesterol ≤ 100 mg, fibre ≥ 8 g, total vegetables ≥ 130 g, sodium chloride equivalent ≤ 3.8 g). IG: received healthy lunch. For analysis, group divided into those who consumed healthy lunch < 50/61 times (< 50%ile) and ≥ 50/61 times (≥ 50%ile) CG: consumed usual lunches without restriction. Nutritional content was assessed. Weekend diet unrestricted for all participants.	TC, LDL, HDL, TG, HbA1c, glucose, leptin, anthropometric data and dietary intake.	CG at 3 months: no significant difference in anthropometrics data; increased SBP (p = 0.063). IG (< 50%ile) at 3 months: decreased DBP (p = 0.000). IG (≥ 50%ile) at 3 months: decreased SBP (p = 0.023), DBP (p = 0,001), TC (p = 0.006) and LDL (p = 0.010) Changes in nutritional intake: energy and carbohydrate intake significantly decreased in IG (< 50%ile); total dietary fibre and vegetables significantly increased in IG (≥ 50%ile).	Japanese-style healthy lunches (consumed consistently) decreased blood pressure and serum lipids and increased plasma ghrelin levels. Our study demonstrates that a short-term intervention consisting of Japanese-style healthy lunches at a workplace cafeteria contributes to lipid metabolism regulation.
Chen et al., 2013 [35]	Taiwan, MetS criteria of the Bureau of Health Promotion in Taiwan [37]	N: 63; (IG: 31 CG: 32) Mean age: CG 45.66 years (SD 8.32); IG: 41.90 years (SD 9.80) Occupation: Full-time career women	3 months	MetS risk factors.	Internet-based tailored health management platform. IG: 3-month intervention focused on nutrition, exercise recommendations and personal advice. CG: no intervention	Changes in health behaviour. MetS risk factors after 3 months (WC, TG, HDL, LDL, FBG, SBP/DBP)	Improvements for IG vs. CG at 3 months: WC (−3.5 vs. −0.6 cm, p < 0.05); fasting glucose (−6.5 vs. −3.1, p < 0.05); mean number of MetS risk factors (−0.6 vs. −0.011, p < 0.05). At 1.5 months, nutrition score had improved in both groups. At 3 months, both groups showed improvements in health behavioural score (p = 0.02), nutrition score (p = 0.02) and mental health score (p = 0.03).	A 3-month internet-based health intervention helped reduce participants’ waist circumference, fasting glucose and number of risk factors for MetS.
Allen et al., 2012 [36]	USA NCEP-ATP-III [35]	N: 64 (IG 26; CG 29) M/F: 6/58 Mean age: 48.9 years Occupation: Employees of the University of New Hampshire Cooperative Extension	12 months	No health status inclusion criteria	The workplace health promotion programme consisted of 10 monthly lifestyle education sessions delivered online and focused on health topics such as CHD risk, diabetes, importance of healthy diet and PA. IG: health risk screening + education sessions + pedometers. Interactive question-and-answer session and sampling of foods. Foods chosen for their nutritional benefit and ease of preparation; healthy snack options. CG: health risk screening + minimal information	1. Percentage-point reduction in LDL-C. 2. 10-year risk for CHD according to Framingham Risk Score (TC, HDL, LDL, glucose, CRP, BMI, SBP/DBP, body fat, cigarette smoking).	After 12 months, mean LDL-c (SD) was significantly lower in IG vs. CG (110.9 [22.2] mg/dL vs. 126.7 [21.8] mg/dL), with a relative difference between groups of 13.4%; no change in CG from baseline. Mean (SD) TC was significantly lower after 12 months in IG (183.4 [22.2] mg/dL) vs. CG (198.6 [20.9] mg/dL); no change in CG from baseline. WC increased in CG and unchanged in IG after 12 months. MetS markers: higher number of markers in CG vs. IG at 12 months (1.9 vs. 1.3). No difference between groups at 12 months in Framingham Risk Score, but absolute reduction of 0.3 points in CHD risk in IG (relative improvement of 18%). Number of steps increased from baseline to 12 months.	Compared with statin administration or lifestyle education in a clinical setting, intervention by videoconference is cost-effective and reduces LDL-c and overall CHD risk.
Nanri et al., 2012 [37]	Japan, Japanese definition of MetS [38]	N: 102 (IG 49; CG 53) M/F: 102/0 Mean age: 53.2 years (SD 6.8, range 38–68]. Occupation: Male employees of company in Japan	6 months	WC ≥ 85 cm plus ≥ 2 MetS risk factors	Lifestyle modification programme based on behavioural change theory. IG: Individual advice for health-related lifestyle changes, including diet and physical activity. Facilitators for behavioural change: pedometers, scales, leaflet and a diary to record behavioural performance and body changes. CG: standard guidelines	1. MetS prevalence at six months. 2. Changes in prevalence of abdominal obesity, dyslipidaemia, BP, hyperglycaemia; and mean change in MetS components (WC, weight, BMI, BP, TC, HDL-c, TG, glucose, HbA1c, CRP).	MetS prevalence did not differ significantly between the two groups (65.3% in IG vs. 62.3% in CG; p = 0,75). No significant differences were observed in BP, TC, HDL-c, TG or glucose. In the IG, intake of cereals and sugar/sweeteners significantly decreased. Rice decreased from 357 g to 297 g (p = 0.004) and PA increased by 57 min/wk (p < 0.001) after 6 months and no change in the control group (p = 0.99).	The intervention did not decrease MetS prevalence. Weight, WC and HbA1c were significantly lower in the IG vs. CG, and the IG made more healthy changes such as reducing sugar, cereals and sweets, and increasing physical activity.
Maruyama et al., 2010 [38]	Tokyo, Japan, NI	N: 87 (IG 52; CG 47) M/F: 87/0 Age range: 30 to 59 years Occupation: Office workers belonging to a health insurance association	4 months	MetS risk factors based on results of regular health check-ups.	Lifestyle modification programme to promote healthy dietary habits and PA. IG: 4 individual counselling sessions with a dietitian and a physical trainer. Participants registered their current targeted food intake and pedometer data on a website for self-monitoring, website advice and personal counselling from the counsellors. CG: no intervention	1. Food group intake and number of steps. Weight, WC, BP, BMI, TC, TG, HDL-c, LDL-c, HA1c, insulin.	Increased consumption of healthy food and decreased consumption of unhealthy food in IG (p = 0.00) but not in CG. Change in number of steps was similar in both groups. Significantly higher percentage of subjects with improvements in clinical parameters in IG compared with CG.	Generalised and relatively simple lifestyle changes, encouraged by a counsellor appear to help prevent metabolic disorders. Interventions based on personal contact and interactive resources are necessary to confirm long-term effects.
Racette et al., 2009 [39]	USA (NCEP-ATP-III) [35]	N: 151 M/F: 17/134 Mean age: 45 years (SD 9) Occupation: employees at selected worksites within a large medical centre	12 months	All employees were eligible.	Health promotion program based on behaviour change theory. IG: assessments + intervention on nutrition and PA + incentives to promote healthy behaviours + pedometers, weekly healthy snack cart, on-site WeightWatchers group meetings and group exercise classes, monthly lunchtime seminars and newsletters, walking team competitions and participation rewards CG: annual health assessment only	1. Weight, BMI, body composition, BP, fitness, lipids, Framingham risk score. 2. TC, HDL-c, LDL-c, TG, FBG. 3. Changes in food group intake and total daily PA	Both groups showed improvements in fitness, BP, HDL-c and LDL-c, and a slight reduction in weight, BMI and fat mass (greater reduction in IG). In the IG, the proportion of participants with the lowest Framingham Risk Score increased from 40% at baseline to 57% after 1 year. The prevalence of MetS reduced significantly in the IG from 38% to 25%, owing to improvements in HDL-c and BP. IG participants also increased fruit and vegetable intake from 4.7 servings at baseline to 7.8 servings at 6 months and 7.0 at 1 year (all p < 0.001); decreased consumption of saturated fat, fatty meals and fried foods (p < 0.001); and significantly increased total daily PA. CG showed significant but smaller improvements in fruit and vegetable intake, saturated fat intake and PA.	Multi-component worksite intervention achieved significant improvements in CVD risk factors and physical fitness. These benefits were attributable to the health assessments and personalized feedback rather than the intervention.

BMI: body mass index; BP: blood pressure; CHD: cardiovascular heart disease; DBP: diastolic blood pressure; FBG: fasting blood glucose; HbA1c: glycated haemoglobin; HDL-c: high-density lipoprotein cholesterol; IDF: International Diabetes Federation; LDL-c: low-density lipoprotein cholesterol; M/F: number of men/number of women; MetS: metabolic syndrome; PA: physical activity; SBP: systolic blood pressure; TC: total cholesterol; TG: triglycerides; WC: waist circumference; NI: nutritional intervention; GI: intervention group; GI1: intervention group 1; GI 2: intervention group 2; CG: control group.