Are Six Meals Better Than Two? Recent Study Shows Lean Mass Gains on Std. Energy-Reduced Diet W/Out Differences in Fat Loss W/ 6 vs. 2 Meals/Day - Do You Have to React?

Do the results of the latest randomized controlled cross-over study from the California State University mean that you have to change your eating habits? Find out in today's SuppVersity Article!
If you are a SuppVersity reader you know that the scientific evidence that eating four meals instead of two when dieting is scarce. More recently, there have actually been more studies to suggest that eating very frequently like 6+ meals per day may eventually ruin your dieting efforts because (a) the constant grazing won't allow your insulin levels to drop and (b) people tend to eat "a little too much" with each of these meals, so that - eventually - they are missing their target energy intakes. Now, an ahead of print article in the peer-reviewed scientific journal Nutrition Research suggests that, in a tightly controlled scenario and with significantly overweight, not to say obese women as subjects, an increase in food frequency from two to six meals per day can have beneficial effects on their weight loss success.
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More specifically, Michelle Kulovitz Alencar et al. (Alencar. 2015) set out to deterimine whether
either a two meal (2MF) or six meal frequency (6MF) regimen can improve body composition and blood-based markers of health while consuming a portion-controlled equihypocaloric diet.
Figure 1: Overview of the study design (Alencar. 2015) | Explanation of the indices: (a) resting metabolic rate, (b) blood pressure (c) visual analogue scale, (d) area under the curve
The study was a randomized-controlled cross-over trial. Thus, the researchers who randomly assigned their N = 11 obese women (52 ± 7 years, 101.7 ± 22.6 kg, 39.1 ± 7.6 kg/m²) who had been to either of the treatment conditions (2MF or 6MF) for two weeks, ensured that by having a washout after the initial two weeks and another two-week intervention phase thereafter, none of the meal frequency patterns had an "unfair" advantage of being "the first" while. Here is an overview of the key facts directly from the research paper:
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    The 2MF pattern participants were instructed to consume allocated meals every 5-6 hours while awake. 
  • The 6MF pattern participants were instructed to consume allocated meals/snacks every 2-3 hours while awake. 
  • Meals provided to participants were defined as an eating occasion with a caloric intake between 200 and 300 kcals, while a snack was defined as an eating occasion with a caloric intake between 100 and 200 kcals. 
  • Throughout all treatment conditions, food products were identical and participants received the identical assortment of pre-packaged food products containing 1,200kcal/day with ~75g/day of protein and a macronutrient ratio of 52% carbohydrates, 27% protein, and 21% fat. 
  • Participants consumed their designated meal pattern eating only Nutrisystem® meal products which were supplied to the participant. Participants also supplemented this diet with a limited selection and quantity of Nutrisystem®-approved fresh fruits and vegetables. The additional fresh items added accounted for only approximately 187 kcals/day, or 15% of daily caloric intake of the participants’ daily total of ~1200 kcals per day. 
  • The participants consumed identical food products throughout the study.
Participants followed their respective MF pattern for the two weeks of Phase I. They the
At the same time a cross-over design like this "virtually" doubles the number of subjects. The same obviously goes for the data Alencar et al. could use to compare the effects of the two meal frequency patterns on body composition, glucose, insulin and lipid components by their individiual responses to a test meal.
Why four meals during the "washout"? During the washout phase participants were instructed to consume the allocated meals and snack (a total of four occasions per day) every 3-4 hours while awake. The washout phase was chosen as 4MF because it was the average number of eating occasions of the participants prior to participation.
Speaking of the effects. As you may have guessed from my preliminary remarks in the introduction, both groups successfully lost (p≤0.05) body mass (=total weight | 2MF: -2.8 ± 1.5 vs. 6MF: -1.9 ± 1.5 kg) - in fact with a slight but highly non-significant "advantage" for the two-meal pattern.
Figure 2: Changes in body composition and resting metabolic rate in both groups (Alancar. 2015).
Since differences in the effects of dieting on glucose, insulin, total-cholesterol, or LDL-C (p>0.05) between the two groups were not observed, one could falsely conclude that the two-meal strategy was in fact minimally more effective.
Figure 3: The fact that we are dealing with body impedence data should make you question the significance of the alleged "lean mass boosting" effects of a 6-meal pattern in people on a calorically reduced diet who are consuming only 75g/day protein total (figure from Alancar. 2015).
It may look like both meal patterns were equally effective... at first sight, at least. If we consider the average fat-free mass (FFM) loss, as well, it is quite obvious that the 6-meal pattern which produced an average increase in fat free mass of 1.2 ± 1.7% (vs. a fat free mass loss of -3.3 ± 2.6% in the two-meal pattern), there is little doubt that in this particular study with this particular subject group, six eating occasions were the superior choice.

A corresponding difference in resting metabolic rate, which reduced by only 4% by the way was yet absent. In addition, the lean body mass benefits were obtained by the means of rather unreliable body impedence analyses (Böhm. 2013; Romero-Corral. 2008) and stands in contrast to the results of several previous studies, which often show different results.

In some cases this may be a consequence of a less rigorous dietary control and the previously hinted at collateral damage due to using each of the six or more eating occasions to eat a little more than ones diet would allow, but that must not necessarily be all. Furthermore, weight and fat loss is not everything. Specifically for obese subjects like the ones in the study at hand, the insulin lowering effects of eating less frequently which are also responsible for the general tendency to be less hungry on energetically reduced diets, can provide another advantage: An increase in heart-healthy HDL cholesterol that was observed in the study at hand only when the subjects were consuming the two-meal pattern. Against this background and evidence from other studies, I caution you against wholeheartedly subscribing to conclusion that this single study would demonstrate, let alone "prove" that a six-meal strategy is the way to go for everyone willing to shed body fat. Higher protein intake, or exercise for example could be game changers. Moreover, for the already lean, the repeated elevations of insulin in response to the frequent meals which were - to my surprise - not observed in the study at hand, but other studies (Fogteloo. 2004 | read more) - may actually hinder the loss of the last slabs of body fat and in the absence of caloric deficits, increased meal frequencies have been linked to increase liver fat and an overall higher obesity risk (Koopman. 2014 | learn more) | Comment on Facebook!
  • Alencar, Michelle K., et al. "Increased meal frequency attenuates fat-free mass losses and some markers of health status with a portion-controlled weight loss diet." Nutrition Research (2015).
  • Böhm, A., and B. L. Heitmann. "The use of bioelectrical impedance analysis for body composition in epidemiological studies." European journal of clinical nutrition 67 (2013): S79-S85.
  • Fogteloo AJ, Pijl H, Roelfsema F, Frölich M, Meinders AE. Impact of meal timing and frequency on the twenty-four-hour leptin rhythm. Horm Res. 2004;62(2):71-8.
  • Koopman, Karin E., et al. "Hypercaloric diets with increased meal frequency, but not meal size, increase intrahepatic triglycerides: A randomized controlled trial." Hepatology 60.2 (2014): 545-553.
  • Romero-Corral, Abel, et al. "Accuracy of body mass index in diagnosing obesity in the adult general population." International journal of obesity 32.6 (2008): 959-966.
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