Will Mounjaro work even if I don't go on a diet?

By Gwynne Sullivan, Amy Nowacoski · last reviewed May 9, 2026

Adapted from the Mounjaro for Diabetes FAQ with permission from the contributing authors.

Potentially for some things, yes. Better results come from diet and exercise. And in diabetes, it is a condition that can get worse. Do yourself favors and make it easier on your body by reading up on and adopting good nutritional habits. People on Mounjaro report anecdotally that it is easier to follow through with dietary decisions, as it takes away some cravings and hunger.

“This study showed overall benefits on glucose and weight lowering, similar to previous phase 2 studies in non‐Japanese participants. In this study, there was also a dose‐dependent association between increased tirzepatide dose and reduced meal intake, suggesting decreased hunger in Japanese participants with T2D. GLP‐1 receptor agonists stimulate satiety and decrease food intake. Likewise, tirzepatide has been shown to suppress food intake and body weight in preclinical studies. In the current study, we found a decreasing trend in fullness (the physical sensation of how much the stomach is filled with food), and no difference in appetite scores among treatment groups. Typically, decreased food intake results in decreased fullness and hence increased hunger; however, tirzepatide appears to decrease the hunger sensation even when the stomach is not filled with food. Interestingly, satiety (the psychological satisfaction of meal intake) appears not to be changed with tirzepatide, even with decreased meal intake and the physical sensation of fullness. Our data support the hypothesis that tirzepatide has effects on hunger and/or the psychological sensation of satiety separate to that induced by physical input from the stomach for meal ingestion, which may result in long‐term effects on meal intake, as reported by the AE of decreased appetite.” A phase 1 multiple‐ascending dose study of tirzepatide in Japanese participants with type 2 diabetes Diabetes Obesity and Metabolism, February 2022 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9299227/

An explainer from 2019. This summarizes what is known versus still being studied regarding the various mechanisms of action that increase metabolism & other elements that induce weight loss by endogenous GLP-1 and recently developed analogues such as tirzepatide: Glucagon, GLP-1 and thermogenesis Int J Mol Sci. 2019 Jul; 20(14): 3445 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6678955/

“In the central nervous system, GLP-1 receptors are located in the hypothalamus, which is involved in regulating food intake [24, 29, 30]. Coveleski et al. found that acute administration of the GLP-1RA exenatide resulted in reduced feelings of hunger in eight women with obesity. The reduced feelings of hunger were associated with an increase in functional connectivity of the nucleus tract solitaries with the hypothalamus and thalamus [31]. In addition, murine models show that liraglutide can access specific brain areas relevant for appetite regulation, binding GLP-1 receptors on proopiomelanocortin and cocaine- and amphetamine-regulated transcript (POMC/CART)-expressing arcuate nucleus neurons [32]. GLP-1 directly stimulates POMC/CART neurons and indirectly inhibits neuropeptide Y (NPY) and agouti-related peptide (AgRP) to increase measures of satiety and decrease hunger [32]. These effects of GLP-1 can lead to reduced energy intake [27], thereby facilitating weight loss (Fig. 1).

…Studies investigating the mechanism of action of GLP-1RA therapy for causing weight loss provide evidence that GLP-1RA treatment is associated with reductions in appetite and hunger, lower preference for energy-dense foods, alteration in food reward pathways, decrease in food cravings, and improvement in eating control.”

Weight Loss and Maintenance Related to the Mechanism of Action of Glucagon-Like Peptide 1 Receptor Agonists Advances in Therapy, 2021 https://link.springer.com/article/10.1007/s12325-021-01710-0