How Much Fat Will You Gain in the Next 6 Months? Your Response to Overfeeding, Low Protein Intakes & Fasting May Tell You If, Yet not How Much Weight You'll Gain

If you oxidize the CHOs from this meal, instead of storing it as glycogen, that's bad news for ability to maintain your body weight over the next 6-months & beyond 

You will know (and maybe hate) them, people who are eating whatever they want, whenever they want while still being not exactly shredded, but at least very lean. What do all these people who have an extremely easy time keeping their weight stable in common?

A recent study from the Phoenix Epidemiology and Clinical Research Branch at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at the "glorious" National Institutes of Health (NIH) suggests that it may relate to the way they respond to fasting and overfeeding on high carb, low protein and eucaloric diets.

I have no idea why the scientists did not modify the protein intake during overfeeding

Are You Protein Wheysting?

5x More Than the FDA Allows!

More Protein ≠ More Satiety

Protein: Food or Supplement?

Protein Timing DOES Matter!

Less Fat, More Muscle!

It is by no means news that there is a considerable inter-individual variation in the energy cost of weight gain. Some people gain weight on a caloric surplus of only 10kcal/day, while others stash away hundreds of extra kcals without gaining a single pound of body fat (these figures have only illustrative values and are not meant to be "exact").

"In a prior cross-sectional study, the increase in energy expenditure (EE) with overfeeding and the decrease with fasting were found to be correlated in a small group of 14 male subjects (Weyer. 2011). Our group has previously shown that the EE response to overfeeding varies considerably among individuals but is consistent and reproducible within individuals. This individual contribution explains more of the observed variability in the EE changes with overfeeding than changes to the macronutrient content of the diet (Thearle. 2013). These studies seem to indicate that phenotypic differences may exist in the EE responses to fasting or overfeeding that may affect susceptibility to weight gain. As overeating or caloric restriction are necessary to alter weight, perturbations in energy balance may be needed to uncover responses that signify an energy conserving physiology versus a physiology that is better able to resist weight gain" (Schlögl. 2015).

In their latest study, Schlögl and colleagues extend their previous findings by addressing the question of whether this inter-individual variation in EE changes relates to future weight change. Or, to put it simply: They tried to answer the question

"Will your acute reaction to 24h overfeeding on different diets predict if you can maintain your weight over the next 6 months, or not?"

To answer the question, the 24-h EE during energy balance during fasting and four different overfeeding diets with 200% energy requirements was measured in a metabolic chamber in 37 subjects with normal glucose regulation while they resided in the clinical research unit of the NIH. Each of the diets was administered for exactly 24h with 3-day washouts in-between (breakfast at 07:00, entry into the calorimeter one hour later; further meals were provided inside the calorimeter at 11:00, 16:00, and 19:00 through a two-door airlock):

• a eucaloric reference diet which was 80% of the weight maintaining diet to account for the reduced energy expenditure due to being confined to the metabolic chamber that contained 50% carbohydrates, 30% fats, and 20% proteins
• a fasting trial (FST) in which the subjects sat in the metabolic chamber fasted
• a low-protein diet (LPF) with 51% carbohydrate, 46% fat, 3% protein
• a standard overfeeding diet (SOF) with 50% carbohydrate, 30% fat, 20% protein
• a high-fat, normal-protein overfeeding diet (FNP) with 20% carbohydrate, 60% fat, 20% protein
• a high-carbohydrate, normal-protein overfeeding diet (CNP) with 75% carbohydrate, 5% fat and 20% protein

To be able to assess the long-term weight gain, all participants returned for follow-up visit to the NIH headquarter 6-months after the initial measures.

Let me highlight the most surprising result in advance: It is really surprising that those with the largest increase in energy expenditure in response to (high carb) overfeeding gained the most amount of weight. Traditionally, we have thought that all that matters was a significant increase in energy expenditure in response to overfeeding that would allow "hard gainers" to simply burn through the extra calories.

On that occasion, their body weight and composition (DXA | unfortunately, the body fat level was not analyzed seperately) was measured and the change in body weight was correlated with (a) the decrease in 24-h EE during fasting and (b) the increase with the different overfeeding protocols.

Figure 1: 24h energy expression expressed relative to eucaloric reference diet (Schlögl. 2015)

The results of the scientists' correlation analysis were surprisingly unambiguous: A larger reduction in EE during fasting, a smaller EE response to low-protein overfeeding and a larger response to high-carbohydrate overfeeding all correlated with weight gain.

Figure 2: Sign. correlations between change in 24-EE during overfeeding / fasting and weight gain (Schlögl. 2015).

If you take a closer look at the correlations (r-values) and their significance in Figure 2 you will realize that all of them are statistically significant . In other words, there is a significant link between an increased risk of gaining weight in the next 6 months and

• a higher decrease in energy expenditure during fasting (Figure 2; A | this should remind you of the thrifty phenotype theory, cf. Wells. 2011)
• a smaller increase in energy expenditure during low protein dieting (Figure 2; B)
• a higher increase in energy expenditure during carbohydrate overfeeding (Figure 2; C)
• a higher higher reliance on fat during fasting (Figure 2; D)

Since the association of the fasting EE response with weight change was not independent from that of low-protein in a multivariate model, there are thus two independent propensities associated with weight gain (1) the very "effective" conservation of energy during caloric and protein deprivation, and (2) the wasteful handling of large amounts of carbohydrates - of these, at least the latter comes as a surprise, doesn't it?

Ha? That's crazy: While finding #1 is neither news nor surprising, it seems very awkward that a large reliance on carbohydrates during fasting and the presence of an increase in energy expenditure during carbohydrate overfeeding correlate with increased weight gain over the next 6 months. I have to admit: I expected the exact opposite.

The correlations observed in the study at hand do not change the previously discussed effects of overfeeding on different macronutrients | more

As Schlögl, et al. point out it is thus "not so much the response to caloric restriction, but rather the response to protein restriction, that defines a “thrifty” phenotype" (Schlögl. 2015). Schlögl et al. also offer an interesting explanation to the counter-intuitive link between increased respiratory quotients and thus increased carbohydrate oxidation and reduced fat oxidation during 24h of fasting which the authors attribute to the "naturally lean" individuals ability to store and thus subsequently more glucose in / from larger glycogen stores. This hypothesis is in line with previous studies that link an increased oxidation vs. storage (as glycogen) of carbohydrate with increased food intakes and weight gain (Pannacciulli. 2007; Zurlo. 1990).

Obviously, this observation leads us right to the one and only way to turn a "thrifty" into a "non-thrifty" (or at least less thrifty) phenotype: Exercise! Exercise increases the amount of muscle to store and the amount of glucose that can be stored on a per kg of lean muscle mass basis. So, if there's a way to turn an "easy-" into a "hard-gainer" it's by building muscle | Comment on Facebook!

References:

• Pannacciulli, Nicola, et al. "The 24-h carbohydrate oxidation rate in a human respiratory chamber predicts ad libitum food intake." The American journal of clinical nutrition 86.3 (2007): 625-632.
• Schlögl, Mathias, et al. "Energy expenditure responses to fasting and overfeeding identify phenotypes associated with weight change." Diabetes (2015): db150382.
• Thearle, Marie S., et al. "Extent and determinants of thermogenic responses to 24 hours of fasting, energy balance, and five different overfeeding diets in humans." The Journal of Clinical Endocrinology & Metabolism 98.7 (2013): 2791-2799.
• Wells, Jonathan CK. "The thrifty phenotype: An adaptation in growth or metabolism?." American Journal of Human Biology 23.1 (2011): 65-75.
• Weyer, C., et al. "Changes in energy metabolism in response to 48 h of overfeeding and fasting in Caucasians and Pima Indians." International journal of obesity and related metabolic disorders: journal of the International Association for the Study of Obesity 25.5 (2001): 593-600.
• Zurlo, Francesco, et al. "Low ratio of fat to carbohydrate oxidation as predictor of weight gain: study of 24-h RQ." American Journal of Physiology-Endocrinology And Metabolism 259.5 (1990): E650-E657.