Capsaicin: 150kcal/d Extra Energy Expenditure, no Effect on Appetite/Hunger in Teens/Twens Receiving 2mg/d, Though

You will remember that this is not the first time capsaicin made it into the SuppVersity news - as a fat burner and potential ergogenic that is | learn more.

That capsaicin is a relatively powerful metabolic isn't news. In Nutrition Research Rigamonti et al. write: "Studies in animals and humans have shown that capsaicin decreases food intake and increases energy expenditure, stimulates fat oxidation, regulates appetite (by decreasing hunger and increasing satiety), and modifies the expression of some hypothalamic peptides implicated in food intake" (Rigamonti 2018) - effects of which the authors highlight that they have been observed in both, lean and overweight adults, but not in "obese adolescents, who are at high risk to become obese adults and for whom effective multidisciplinary integrated body weight reduction programs are needed" (ibid).
What makes capsaicin particularly attractive as a weight loss adjuvant is its ability to do both: increase your energy requirements and suppress your appetite. The previously referenced >150kcal/d increase in resting energy expenditure, for example, would be worth nothing if people simply compensated by eating more... with its effect on satiety hormones and gastric emptying, capsaicin has been found to prevent that and thus to induce an effective (albeit small) caloric deficit.

Figure 1: Therapeutic role of capsaicin in various pathological conditions (Patowary 2018).

Don't forget, though: The word "small" is important, here. After all, conventional wisdom tells you that you'd have to wait for 20 days to shed only 1lbs of fat if your deficit is only 150kcal/d (we all know that this is just a very rough estimate, don't we?). That's not super-impressive, but it would be better than not losing any body fat.
But I am going too fast here. Before we talk about the implications in the bottom line, let's initially take a look at the methodology:

"[...]the aim of the present study was to evaluate the acute effects of capsaicin (2 mg) or placebo on energy intake, hunger and satiety in obese adolescents and young adults (F/M = 4/6, age: 21.0±5.8 yrs; BMI: 41.5±4.3 kg/m2), provided an ad libitum dinner" (Rigamonti 2018). 

To identify what's driving the changes in energy expenditure and appetite, the authors analyzed the circulating levels of some orexigenic (ghrelin) and anorexigenic (GLP-1 and PYY) peptides after a meal (lunch). Together with the evaluation of hunger and satiety and assessment of resting energy expenditure (REE) through indirect computerized calorimetry, the analysis of the corresponding data produced two rather disappointing results:

• When compared to placebo, capsaicin did not significantly change either energy intake or hunger/satiety six hours after its administration (dinner). 
• No differences in circulating levels of ghrelin, GLP-1, and PYY and in hunger/satiety were found in the three hours immediately after food ingestion among obese subjects treated with capsaicin or placebo (lunch). 

References:

• Patowary, Pompy, et al. "Research progress of capsaicin responses to various pharmacological challenges." Biomedicine & Pharmacotherapy (2017).
• Rigamonti, et al. "Acute administration of capsaicin increases resting energy expenditure in young obese subjects without affecting energy intake, appetite and circulating levels of orexigenic/anorexigenic peptides." Nutrition Research. Available online 10 February 2018 - In Press, Accepted Manuscript.