Weekends sabotage weight loss attempts

You’re doing your best to lose weight, but it’s going so slowly – you just wish those excess rolls of fat would disappear more quickly. An American study published in 2008 suggests that things go wrong during the weekend.

In 2008, nutritionist Susan Racette, of Washington University in St Louis, published the results in Obesity of a yearlong experiment involving 48 subjects aged between 50 and 60, most of whom were overweight.

Nineteen of the subjects lost weight that year by eating less [CR]. Another 19 lost weight by exercising more [EX]. The ten people in the control group made no attempt at all to lose weight [HL].

Those who ate less lost 8.0 kg, those who exercised more 6.4 kg. The researchers monitored their subjects so closely that they were able to see that weight loss stopped during the weekend. In fact the weight-losers actually put on weight at weekends.


The figures below show how this happened. On Saturdays and Sundays the subjects’ energy intake rose. They had apparently decided they could treat themselves to calorie-rich food.


The exercisers lost 0.32 kg on Monday, Tuesday and Wednesday, but were 0.24 kg heavier on Friday, Saturday and Sunday. The dieters lost 0.28 kg on Monday, Tuesday and Wednesday, but put on 0.06 kg on Friday, Saturday and Sunday. So at weekends not only does weight loss stop, but some of the loss is actually put back on.

The researchers monitored their subjects before they started their weight-loss attempts. During that period the weekend effect was even stronger. Not only did the calorie intake peak, but on Sundays calorie expenditure also went down. The combined effect of these two phenomena was so strong that the subjects could potentially gain 4 kg in a year.


Many weight loss experts and dieticians tell those wanting to lose weight that they can eat what they want at weekends. No doubt this is psychologically a good idea, because it makes it easier to stick to a diet. But Racette’s research shows that weight losers need more eating discipline at weekends, not less.

“Weekend dietary indulgences contribute to weight gain or cessation of weight loss”, the Americans write. “Our results support the importance of maintaining consistent dietary and physical activity patterns throughout the week to avoid unwanted weight gain and to facilitate consistent weight loss.”

Maybe dieticians could advise weight-losers to restrict their ‘free choice moments’ to one hour a week, or to just one meal.

Influence of weekend lifestyle patterns on body weight.


To determine whether alterations in diet and/or activity patterns during weekends contribute to weight gain or hinder weight loss.

Randomized, controlled trial comparing 1 year of caloric restriction (CR) with 1 year of daily exercise (EX). Subjects included 48 healthy adults (30F, 18M) aged 50-60 years with BMI 23.5-29.9 kg/m(2). Body weight was measured on 7 consecutive mornings for a total of 165 weeks at baseline and 437 weeks during the 1-year interventions. Daily weight changes were calculated for weekends (Friday to Monday) and weekdays (Monday to Friday). Daily energy intake was estimated using food diaries; daily physical activity was measured using accelerometers. Both measures were validated against doubly labeled water (DLW).

At baseline, participants consistently gained weight on weekend days (+0.06 +/- 0.03 kg/day, (mean +/- s.e.), P = 0.02), but not on weekdays (-0.02 +/- 0.02 kg/day, P = 0.18). This was attributable to higher dietary intake on Saturdays and lower physical activity on Sundays relative to weekdays (both P < 0.05). During the interventions, both CR and EX participants were in negative energy balance on weekdays (P < 0.005). On weekends, however, CR participants stopped losing weight, and EX participants gained weight (+0.08 +/- 0.03 kg/day, P < 0.0001) due to higher dietary intakes on weekends. This helps to explain the slower-than-expected rate of weight loss during the interventions. DISCUSSION: Alterations in lifestyle behaviors on weekends contribute to weight gain or cessation of weight loss on weekends. These results provide one explanation for the relatively slow rates of weight loss observed in many studies, and the difficulty with maintaining significant weight loss. PMID: 18551108 [PubMed - indexed for MEDLINE] PMCID: PMC3740215 Source: http://www.ncbi.nlm.nih.gov/pubmed/18551108