Supplementation of Gut-brain Axis (GLP-1)-Activating Carbohydrates for Increasing Satiety in Adolescents With Obesity (GUT BOOST)

Glucagon-like peptide-1 (GLP-1) receptor agonist drugs, such as semaglutide and tirzepatide, have quickly become a standard treatment for adults with obesity. Adolescents, on the other hand, have limited access to FDA-approved medications for obesity, even though semaglutide has been shown to lead to significant improvements in body mass index and co-morbidities of obesity for youth over age 12. Obesity is defined as a body mass index greater than the 95th percentile for age and sex. Moreover, GLP-1 agonists are effective in reducing appetite and food intake and result in notable weight reduction. These drugs trigger an innate physiological system of the body that, among other targets, signals the appetite control center of the brain, the hypothalamus, to convey a feeling of fullness, as well as to slow the rate of stomach emptying. This "gut-brain axis" communication system is naturally activated by digested macronutrients through their interaction with the enteroendocrine cells, particularly the L-cells which are found in greater abundance in the distal small intestine (ileum) and proximal colon. For over 15 years, the Hamaker Lab at Purdue University has researched the potential of ileal-digesting carbohydrates, such as certain types of starch, in activating L-cells to secrete GLP-1 as a dietary route towards appetite control. In long-term feeding rat and mouse trials, the investigators have shown ileal activation of the gut-brain axis and sustained increase in plasma GLP-1 that coincided with reduction in food intake and weight management using developed methods to target starch digestion to the ileum (a starch-based fabricated microsphere and precise a-amylase inhibition to slow starch digestion. Additionally, short-chain fatty acids (SCFAs) produced by dietary fiber fermentation by gut microbes trigger secretion of GLP-1 for satiation. SCFAs also reduce gut inflammation that is linked to obesity. Of note, there are other gut hormones secreted by L-cells (e.g., Gastric Inhibitory Polypeptide (GIP), Peptide YY (PYY), oxyntomodulin) that influence the gut-brain axis for appetite modulation.

Interestingly, in mouse trials with fabricated ileal-digesting carbohydrates for gut-brain axis activation, the investigators also found reduction in fatty livers of obese mice.

Even though GLP-1 agonist drugs are highly effective in reducing weight in individuals with obesity and lowering indices of associated health conditions (e.g., Hemoglobin A1c for prediabetes/diabetes), most individuals cannot remain on the medication indefinitely due to expense and side effects, and some simply prefer not to take the weight-reducing drugs, especially at a younger age. It is, therefore, timely to test a dietary approach to activate the innate GLP-1-secreting cells in the gastrointestinal tract, through a safe and inexpensive science-based carbohydrate supplement the investigators have tested and partly optimized.

For the current proposal, the investigators hypothesize that a mixture of ileal and colonic gut brain axis (GLP-1)-activating carbohydrates given as a supplement for two months to adolescents with obesity will increase plasma GLP-1 levels, increase satiation, decrease caloric intake, reduce body mass index percentile (BMI%ile), attenuate gut inflammation, and lower liver fat.

Our overall objective is to test a combination of two food carbohydrates designed to activate the gut-brain axis through GLP-1 release for physiologic appetite suppression. The investigators will examine the central hypothesis that carbohydrates that modulate the gut-brain axis represent an efficacious strategy by which to reduce appetite and body weight in adolescents with obesity.