Thursday, March 6, 2014

Grazin' Study Shows: Increased Eating Frequency Bad For Obese and Lean Men. Reduced Diet-Induced Thermogenesis and Blunted Lipolysis Could Promote Future Weight Gain

Grazing not allowed!
Usually, I don't do this in the introduction of an article, but in this case, it fits so nicely that I just can't resist to prepend todays SuppVersity article with a citation from the conclusion of a recent paper in Pyschology and Behavior, a journal of which I believe that it covers the true reasons of the obesity pandemic... but I am digressing, here's your quote (Allroit. 2014):
"Even if subjective and physiological data suggest a beneficial effect of frequent eating on appetite in obese men, no effect was demonstrated on energy intake. Moreover, the decrease in diet induced thermogenesis and lipolysis, reflected by NEFA profiles, could be deleterious on energy balance in the long run."

What? Grazing ain't good for me? But my doctor (Oz?) said so!

If you are still in the "I believe every word my doctor" says phase of your development as a free-thinking individual, it's probably a waste of time to read the rest of the article. If you have an open ear and eye for the scientific discoveries that have been made in 25 years that have been passed since the 5th edition of the by then already outdated textbook your doctor used during his studies were published, I'd suggest you take a look at the overview of the study design:
"[A]fter being included, the subjects had a first visit for a lunch at the experimental restaurant of Institut Paul Bocuse Research Centre (IPB). The aim of this first visit was to familiarize the subjects with the environment and the foods which would be used during the study.

During this visit, subjects were invited to the experimental restaurant at 12:00 and were asked to taste all of the food items offered at an individual buffet-type meal. A choice of classical hot and cold French food items with varied macronutrient compositions was offered. [...] Subjects were instructed to eat ad libitum. The mean rating of food items, measured on a 100 mm electronic visual analog scale (VAS), varied from 4.4 ± 0.4 (for grated carrots), to 7.5 ± 0.4." (Allriot. 2014)
After this first visit, the subjects were then invited to four experimental sessions, in a randomized order, each session separated by at least 7 days: two were conducted in IPB for behavioral explorations; the other two took place in Rhône-Alpes Research Centre for Human Nutrition (CRNH) for metabolic explorations.
Please note: What the scientists observed in the study at hand, as well as in their previous research does not confirm that eating more frequently will make you obese. It does however provide significant evidence against the "eat more frequently to stay lean"-hypothesis that's still rattling around in the mainstream media and certain parts of the fitness community.
At first this may seem awkward, but by having four sessions in different locations the scientists tried to minimize environmental confounders. Furthermore, the order of the four testing sessions was randomized across the participants to prevent any order effect (the random allocation sequences were generated by a biostatistician using a 2-step randomization).
  • Subjects were requested to avoid vigorous activities and to abstain from alcohol consumption the day before each session. 
  • Subjects were also asked to select a dinner they consume regularly and to eat this same meal the evening before each session. 
  • Subjects were also instructed tofinish eating this dinner by 9:00 pm and to eat nothing else after this time. 
For the four sessions, the subjects were given each time the same 674.8 kcal breakfast, the sole difference - you probably suspected this already, when you read the quotation in the introduction to this article - was the time they had to consume this meal, i.e.
  • 20 min in  T0 (8:00 am) (F1 condition) or 
  • 4x10 min long (168.7 kcal each) every hour at T0, T60, T120 and T180 min (F4 condition). 
The breakfast in F1 was composed of white bread (40 g), croissant (80 g), strawberry jam (30 g), unsalted butter (10 g), orange juice (120 g), white sugar (10 g), and black coffee or tea (400 ml). For each of the four eating episodes of F4, these quantities were divided by 4. Subjects were asked to eat all the food provided for breakfast. As mentioned earlier, they received both breakfasts (F1 and F4) on two occasions: once in the IPB, once in the CRN.

Ok, you know the results, but ....

... let's still take the time and check out the quantitative differences between the metabolic response to grazing (F4 condition) vs. regular food consumption (F1) in the 17 obese male study particpants (BMI 31.9kg/m²).
Figure 1: Subjective satiety and hunger scores in the obese subjects during the 2x2 testing conditions (Allriot. 2014)
What is certainly interesting, is that even the subjective advantages in hunger and satiety were very transient and, if you take a look at what the subjects ate, you will probably argue that this is no wonder: I mean, you don't believe you can gobble down white bread, a croissant with strawberry jam and unsalted butter and a cup of sugar-sweetened coffee all at once without a significant elevation in insulin of which you as a SuppVersity reader know that its satiety effects are blunted in obese / insulin resistant individuals, do you?
Figure 2: Insulin (left) and NEFA (right) levels after the test-meals (Allriot. 2014)
While I am not sure how differences such as those you see in Figure 2 were statistically non-significant, I can tell you that the increase in NEFAs in the "regular eaters" (F1) at T ~ 220min goes hand in hand with the previously reported increase in fatty acid oxidation that was - just as the increase in NEFA - blunted, when the subjects "grazed" their breakfast.
Bottom line: You want it really short? Don't fu**** graze / eat 10x a day! Despite the beneficial impact on appetite sensations and on ghrelin and GLP-1 concentrations, this study provides evidence that an isocaloric increase of the number of eating episodes does not have a short term positive effect on energy intake in obese men.

Suggested Read: " "Breakfast Keeps You Lean" Myth or Mystically True? Bias + Unwarranted Causal Implications" | read more
Contrary to what the authors write in their conclusion, this does eventually stand in line with findings in lean individuals, where a similar reduction in dietary thermogenesis and inhibited lipolysis was observed (Allirot. 2013). This is obviously of paramount importance for us, because it confirms that "the beneficial short-term effect of increasing eating frequency on appetite in lean men considering subjective, physiological and behavioral data" are not worth the anti-weight loss effects due to the reduced thermogenecis and decreases in lipolysis "that could be deleterious on energy balance in the long run." (Allriot. 2013) - for once, I have nothing to add, here ;-)
  • Allirot, Xavier, et al. "An isocaloric increase of eating episodes in the morning contributes to decrease energy intake at lunch in lean men." Physiology & behavior 110 (2013): 169-178.
  •  Allirot, Xavier, et al. "Effects of a breakfast spread out over time on the food intake at lunch and the hormonal responses in obese men." Physiology & behavior (2014).