In Western civilization, the three daily meals – breakfast, lunch, and dinner, as we know them today – have been the gold standard” of eating since probably late 18th to early 19th century.1 However, in more recent times, the method of increased eating frequency (i.e., eating small amounts of food every 2–3 hours) has gained popularity as strategy for managing hunger and/or losing weight.2,3 And even more recently, intermittent fasting has risen in popularity as a tool for weight maintenance and weight loss.4 So, which strategy is the best for weight loss? All of them….and none of them. It would seem that a reduction in calories and adherence to the weight loss plan are the cinchers to successful weight loss, not the timing or frequency of eating or fasting.
Meal frequency.
Eating frequently during the day, or “grazing,” has been proposed to assist with managing food intake and weight.2,3 However, in a 2015 systematic review that assessed the effects of greater eating frequency on food intake and body size in human and animal experimental studies, eight out of 13 examined studies reported no significant effect of eating frequency on food consumption rates, and 11 out of 17 studies found no significant effect of eating frequency on body size.5 In another meta-analysis published in 2015, the authors examined research on meal frequency with respect to changes in fat mass and lean mass. Here, the authors did find a positive association between meal frequency and reductions in fat mass and body fat percentage, as well as an increase in fat-free mass. However, further analysis of the data showed that these positive findings were the product of a single study, which, according to the authors, cast doubt as to whether more frequent meals actually did confer beneficial effects on body composition.6 And finally, according to a 2007 study from the University of Ottawa, there was no weight loss advantage to splitting calories among six meals rather than three, nor did the authors find favorable effects of increased meal frequency on appetite and PYY levels (PYY or peptide YY is a short [36-amino acid] peptide released from cells in the ileum and colon that acts to reduce appetite in response to feeding.)7
On the other hand, research has found benefit to eating six meals a day over three meals a day in other ways. According to a randomized trial published this year, investigators compared the effects of two eucaloric (i.e., calories in is balanced with energy out) meal patterns (3 vs. 6 meals/day) on glycemic control and satiety in patients with obesity and early stage Type 2 diabetes (T2D). So, while the authors report that weight loss remains “the key strategy in hyperglycemia management,” and the meal plans employed in the study were not geared toward weight loss, “…six meals versus three meals day can increase glycemic control in obese patients with early-stage T2D, and might improve and/or stabilize postprandial glucose regulation in prediabetes subjects.”8
Intermittent fasting.
A 2017 article published in JAMA Internal Medicine reported the results of a randomized, clinical trial that compared the effects of alternate-day fasting with daily calorie restriction on weight loss, weight maintenance, and indicators of cardiovascular disease risk. Trepanowski et al included 100 metabolically healthy adults with obesity in their study. Participants were randomized to one of three groups for one year: alternate-day fasting (25% of energy needs on fast days; 125% of energy needs on alternating “feast days”), calorie restriction (75% of energy needs every day), or a no-intervention control. The trial involved a six-month weight-loss phase followed by a six-month weight-maintenance phase. The researchers found that the mean weight loss was similar for participants in the alternate-day fasting group and those in the daily calorie restriction group at Month 6 and Month 12. Additionally, there were no significant differences between the intervention groups in blood pressure, heart rate, triglycerides, fasting glucose, fasting insulin, insulin resistance, C-reactive protein, or homocysteine concentrations at Month 6 or 12. Interesting to note, however, that the dropout rate was highest among alternate-day fasting group, which suggests that this regimen might be more difficult to adhere to compared to daily calorie restriction.
So, what’s the best plan to follow to lose weight?
In a 2014 analysis of data from nearly 50 trials that totaled about 7,300 individuals, Johnston et al observed significant weight loss using any low-carbohydrate or low-fat diet, with only very small differences being observed between the diet programs, which supports the practice of recommending any calorie-restricted diet to which a patient will most likely adhere to lose weight.10
Summary.
In summary, research supports that whether you choose a weight loss plan that incorporates the three-meal-a-day, six-meal- a-day, or intermittent-fasting strategy, as long as you take in fewer calories than you burn, you can lose weight. However, there is evidence supporting that more frequent meals, while not necessarily effective for weight loss, might be beneficial in hyperglycemia management. Before choosing a weight loss strategy, make note of the eating frequency prescribed in the diet(s) you are considering and ask yourself if the strategy is realistically doable for you for the next several weeks to several months (be honest!). Next, it would be prudent to seek advice from your physician regarding the strategy you intend to follow. And finally, remember: It would seem that the most effective weight loss strategy, plain and simple, is sticking to a balanced, healthy diet while maintaining a calorie deficit.
