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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.
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.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)

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.

Probiotics act on in the digestive tract, but their effects are still systemic.

You've read about the anti-weight gain effects of probiotic supplements in rodents before at the waredownloadsoft and in the waredownloadsoft Facebook News. Nice, yes, but will this also work in human beings? If we put faith into the predictive quality of a recent from Virginia Tech, it should.

Before we delve deeper into the study design, results and evaluation in the bottom line, I'd yet like you to know that (a) we don't know if the effects will persist for more than 4-weeks, if they will become stronger or weaker and that (b) the study was funded by VSL Pharmaceuticals (Osterberg. 2015) - both additional reasons not to confuse a single study like this with "proof" that probiotics block fat gain.
The objective of Osterberg's latest study was to "determine the effects of the probiotic, VSL#3, on body and fat mass, insulin sensitivity, and skeletal muscle substrate oxidation following 4 weeks of a high-fat diet" - in humans, and even better in 20 non-obese men (18-30 years) who participated in the study.

Learn everything about overfeeding! How do the effects of high vs. low fat, high vs. low protein and high vs. extra-high energy intake differ, what's the effect on thyroid and other important hormones and more

"All testing took place at the Human Integrative Physiology Laboratory between the hours of 5:00 and 11:00 am. Participants fasted for 12 h, did not consume caffeine or alcohol, performed no vigorous physical activity for the prior 48 h, and were free from acute illness for the prior 2 weeks.

[...]Following a 2-week eucaloric control diet, participants underwent dual X-ray absorptiometry to determine body composition, an intravenous glucose tolerance test to determine insulin sensitivity, and a skeletal muscle biopsy for measurement of in vitro substrate oxidation" (Osterberg. 2015). 

Subsequently, participants were randomized to receive either VSL#3 (2x450 billion bacteria), a dietary probiotic supplement that contains a motley mix of bacteria, i.e. Streptococcus thermophilus DSM24731, Lactobacillus acidophilus DSM24735, Lactobacillus delbrueckii ssp. bulgaricus DSM24734, Lactobacillus paracasei DSM24733, Lactobacillus plantarum DSM24730, Bifidobacterium longum DSM24736, Bifidobacterium infantis DSM24737, and Bifidobacterium breve DSM24732, or placebo daily during 4 weeks.

Figure 1: Composition (in g/day) and energy consumption (kcal/day) of the lead in and high fat diet (Osterberg. 2015).

Both, i.e. the probiotic supplement VSL#3 as well as the placebo supplement, were consumed alongside a high fat milk shake which also served to bring up the total energy intake (+1,000kcal/day) and relative contribution of fat from 8% to 55% compared to the standardized diet that was used in the 2-week lead in. Practically speaking, we are thus looking at a standardized high fat overfeeding study with or without probiotic intervention.

Figure 2: Changes in body composition in response to 4-week high fat overfeeding with or without probiotic supplementation (VSL#3, a 900 billion multi-strain probiotic) in 20 normal-weight young men (Osterberg. 2015).

A study that yielded interesting results, but results that are of questionably practical relevance. Yes, there was a statistical group effect for the changes in total body mass (0 kg vs. 0.8kg) and the total body fat mass (+1.1% vs. +2.4%).

Since there were neither significant differences in body fat% due to the lower lean mass gains in the probiotic group and considering the fact that there were no additional health effects in form improvements in insulin sensitivity or fat oxidation. Since neither of them was affected by the overfeeding, anyways, the significance of the lack of change is questionable.
References:

• David, Lawrence A., et al. "Diet rapidly and reproducibly alters the human gut microbiome." Nature 505.7484 (2014): 559-563.
• Osterberg, et al. "Probiotic Supplementation Attenuates Increases in Body Mass and Fat Mass During High-Fat Diet in Healthy Young Adults." Obesity (2015): Ahead of print.