. 2017 Jul 4;2017:2085136. doi: 10.1155/2017/2085136

Table 2.

Studies evaluating the effect of the holiday period on body weight in adults attempting to lose weight or motivated self-monitoring people.

Author, year, and country	Number of participants, age, sex, BMI, and prevalence of overweight/obesity	Date of measurements^a	Sample, masking of participants, retention^b	Mean weight change ± SD	p value^c
Andersson and Rössner 1992 Sweden	46 adults 20–70 years Men = 28% Women = 72% BMI = 36.8 ± 6.6 kg/m² Obese = 100% 76 adults 20–70 years Men = 28% Women = 72% BMI = 22.9 ± 2.6 kg/m² Obesity not reported	Initial measurement: before Christmas. Final measurement: after January 6th. (3 weeks between data collected).	Subjects participating in a maintenance program for obesity. Masking only in this group. Subjects from the hospital staff who participated as control group (not attempting to lose weight). Yes. Retention not reported.	0.6 ± 2.4 kg 0.4 ± 0.8 kg	NS p < 0.001

Boutelle et al. 1999 United States	57 adults 44.5 ± 10.0 years Men = 28% Women = 72% BMI = 35.5 ± 7.3 kg/m² Obese = 100% (initial BMI 35.5 ± 7.3 kg/m² and a mean weight loss of 15.1 ± 12.4 kg)	Specific dates not reported, but describe changes during 8 weeks of holiday season (early December to last days of January).	Subjects participating in long-term cognitive-behavioral treatment program, assigned to receive an intervention for improving consistency of self-monitoring. Subjects participating in long-term cognitive-behavioral treatment program without receiving the intervention for improving consistency of self-monitoring. No. Retention 88%.	−0.9 ± 2.45 kg 0.9 ± 3.49 kg	p = 0.007 (between groups comparisons)

Watras et al. 2007 United States	22 adults 18–44 years Men = 23% Women = 77% BMI = 27.6 ± 1.8 kg/m² Overweight = 100% 18 adults 18–44 years Men = 17% Women = 83% BMI = 28.0 ± 2.2 kg/m² Overweight = 100%	Specific dates of measurements not described, but reported the increase in kg/month during holiday season (November and December).	Subjects who participated in a randomized trial evaluating conjugated linoleic acid for fat loss Subjects from the placebo control group. No. Retention 83%.	−0.1 kg^d 0.6 kg^d	p = 0.01 (between groups comparisons)

Squires 2007 United States	217 adults Age, sex, BMI, and prevalence of overweight/obesity not reported	Initial measurement: at the beginning of the challenge. Final measurement: at the end of the challenge. (data collected between Thanksgiving and New Year).	Subjects participating in a weight maintenance challenge. No. Retention 75%.	−1.0 kg^d	NR

Phelan et al. 2008 United States	167 adults 47.5 ± 11.5 years Men = 25% Women = 75% BMI = 25.5 ± 6.4 kg/m² Obese = 100%, (maximum BMI = 37.4 ± 9.4 kg/m² and a mean weight loss of 34.9 ± 16.5 kg) 90 adults 45.5 ± 13.9 years Men = 25% Women = 75% BMI = 21.8 ± 1.9 kg/m² Normal weight = 100%	Initial measurement: early November. After holiday measurement: early January.	Successful weight losers from the National Weight Control Registry. Normal weight individuals not attempting to lose weight. No. Retention 94% and 89%.	0.7 ± 1.8 kg 0.2 ± 1.0 kg	NS NS

García et al. 2013. Spain	215 adults 14–70 years Men = 37% Women = 63% BMI = 28.0 ± 2.22 kg/m² Overweight or obese = 100%	Initial measurement: a couple of days before December 25th. Final measurement: a couple of days after January 5th. (2 weeks between measurements).	Individuals receiving treatment for obesity No. From 258 patients, 215 were measured on both occasions.	0.29 ± 1.33 kg	p < 0.05

Helander et al. 2016. United States, Germany and Japan	United States: 1781 adults Age = 42.2 years Men = 66% Women = 34% BMI = 27 ± 5.2 kg/m² Obese = 24% Germany: 760 adults Age = 42.9 years Men = 66% Women = 34% BMI = 26.6 ± 4.9 kg/m² Obese = 19% Japan: 383 adults Age = 41.6 years Men = 74% Women = 26% BMI = 24.7 ± 4.7 kg/m² Obese = 11%	Initial measurement: ten days before Christmas. Final measurement: ten days after Christmas.	From a random sample of 10,000 Withings weight scale users, 2924 subjects were analyzed after the exclusion criteria were applied. Yes.	United States: 0.4% kg^d,e Germany: 0.6% kg^d,e Japan: 0.5% kg^d,e	p < 0.001 p < 0.001 p = 0.005

^aWeight of participants in all studies was measured as part of the study, except for Andersson and Rössner 1992 (self-report in individual charts), Phelan et al. 2008 (self-report via questionnaire), and Helander et al. 2016 (scale saves the weight of the individual and sends it to network servers). ^bMasking: the participants did not know that the study objective was to evaluate the effect of holidays on obesity parameters; ^cp value derived from comparisons before and after analysis, except when specified; ^dSD not reported. ^eWeight reported by percent of weight, because authors of the study did not report kilograms; BMI: body mass index. NS: not significant. NR: not reported.