For instance, a 6-week study in 66 people with type 2 diabetes found that taking 30 grams of glutamine powder daily improved multiple risk factors for heart disease and reduced both belly and body fat ( Similarly, a 2-week study using the same amount of glutamine observed decreased waist circumference, a marker for belly fat, in 39 people with overweight or obesity ( In another small study, 6 women who took glutamine supplements for 4 weeks experienced significant reductions in body weight and belly fat without making other dietary or lifestyle changes ( Yet, a study in 24 adults indicated that taking 6 grams of glutamine led to an increase in meal size, which may hinder weight loss ( Moreover, another study that examined the effects of taking a glutamine supplement in combination with exercise noted no benefits for body composition or muscle performance ( Keep in mind that all of these studies used very small sample sizes and only evaluated the short-term effects of glutamine supplements

Clinical trials found about 13.6% average body weight reduction with the oral form and about 14.9% with the injection, though the trials weren't designed for a direct comparison
doi:10.1067/mpd.2001.114480
Incorporate light exercise: In a review of 12 studies, every one of them showed that physical activity was associated with fewer feelings of low energy and fatigue
Notably, SCFA-mediated GLP-1 release was abolished in Gpr43 -deficient mice, confirming receptor dependency (Psichas et al., 2015)