BATON ROUGE, La. – Researchers found that tirzepatide, a medication primarily used for treating type 2 diabetes and weight loss, reduced body weight, food intake and many measures of appetite more than placebo and liraglutide. These results were recently published in Nature Medicine in the study titled “Tirzepatide on ingestive behavior in adults with overweight or obesity: a randomized 6-week phase 1 trial.”
Pennington Biomedical’s Dr. Owen Carmichael, Director of the Biomedical Imaging Center, and Dr. Corby Martin, Director of the Ingestive Behavior, Weight Management & Health Promotion laboratory, along with collaborators from research institutes across the country, evaluated tirzepatide against liraglutide and a placebo. Significant results started emerging on the third week of the six-week trial, and participants taking tirzepatide ate 72% less calories than they did before taking the medication. Tirzepatide decreased numerous measures of appetite or the drive to eat, including things like hunger and food cravings. Interestingly, tirzepatide did not increase the intent to restrict food intake, which is a novel finding.
“For people to lose weight, they typically spend a great deal of effort trying to limit how much they eat,” said Dr. Martin. “Tirzepatide promotes weight loss and large reductions in food intake, with apparently little volitional effort among participants. This is indeed novel.”
Study participants were examined with functional magnetic resonance imaging (fMRI) to analyze brain activity while being shown pictures of a variety of foods, including cakes, ice cream, and other foods high in fat and sugar. The brain scans demonstrated that individuals taking tirzepatide exhibited reduced activity in hunger and reward sensitive brain areas while viewing such high-fat, high-sugar foods.
“We believe this may be the first data suggesting that tirzepatide modifies brain functioning in eating-relevant brain regions more than liraglutide does,” said Dr. Carmichael. “It was already well established that tirzepatide promotes greater weight loss on average than liraglutide does, but it was not entirely clear why. Our data suggests that one reason for tirzepatide’s greater efficacy could by that it has a great greater effect on brain function.
Unlike semaglutide or liraglutide that only activate the GLP-1 receptor, the dual agonist tirzepatide works on the GLP-1 and GIP receptors, two important hormone pathways that help control hunger. As of today, there are no medications on the market that purely target GIP, which may indicate a new direction for research possibilities.
“For those living with obesity or diabetes, the field of weight loss medications is at an inflection point, in which we are seeing results improve further as new products are tested and become available,” said Dr. John Kirwan, Executive Director of Pennington Biomedical. “I congratulate Drs. Carmichael and Martin, along with their collaborators, on this new study, as the data indicates that tirzepatide is highly effective at managing appetite and food intake and has measurable effects on brain responses to food.”
About the Pennington Biomedical Research Center
The Pennington Biomedical Research Center is at the forefront of medical discovery as it relates to understanding the triggers of obesity, diabetes, cardiovascular disease, cancer and dementia. Pennington Biomedical has the vision to lead the world in promoting metabolic health and eliminating metabolic disease through scientific discoveries that create solutions from cells to society. The center conducts basic, clinical, and population research, and is a campus in the LSU System.
The research enterprise at Pennington Biomedical includes over 600 employees within a network of 44 clinics and research laboratories, and 16 highly specialized core service facilities. Its scientists and physician/scientists are supported by research trainees, lab technicians, nurses, dietitians, and other support personnel. Pennington Biomedical is a globally recognized state-of-the-art research institution in Baton Rouge, Louisiana.
For more information, see www.pbrc.edu.
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Media Contacts:
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Journal
Nature Medicine
Method of Research
Randomized controlled/clinical trial
Subject of Research
People
Article Title
Tirzepatide on ingestive behavior in adults with overweight or obesity: a randomized 6-week phase 1 trial
Article Publication Date
24-Jun-2025
COI Statement
The institution of C.K.M. is supported by NORC Center Grant P30 DK072476 entitled Nutrition and Metabolic Health Through the Lifespan sponsored by NIDDK and by grant U54 GM104940 from the National Institute of General Medical Sciences, which funds the Louisiana Clinical and Translational Science Center. C.K.M. declares research funding from Eli Lilly and Company paid to his institution to perform the work described in this paper; research grants or contracts paid to his institution from Pack Health, American Society for Nutrition, RAND Corporation, Richard King Mellon Foundation (RKMF), Evidation Health, Leona M. and Harry B. Helmsley Charitable Trust, State of Louisiana Federal American Rescue Plan (ARP), USDA, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., University of Rochester (NY), Foundation for Food and Agriculture Research, Kroger Co. Zero Hunger/Zero Waste Foundation, National Institute for Health Research (NIHR), Weight Watchers, American Diabetes Association, Eli Lilly and Company, National Science Foundation (NSF) and National Institutes of Health (NIH); royalties from ABGIL; personal consulting fees from EHE Health and WondrHealth; honoraria from Obesity Action Coalition, Indiana University Bloomington, University of Alabama at Birmingham, Nutrition Obesity Research Center, Brigham Young University, University of Kansas Medical Center (KUMC), University of Southern California and Commission on Dietetic Registration; travel support from Indiana University Bloomington, University of Alabama at Birmingham, Nutrition Obesity Research Center, Brigham Young University, University of Kansas Medical Center (KUMC), University of Southern California and Commission on Dietetic Registration; provision of research materials from Eli Lilly and Company and Weight Watchers; participation on advisory boards for Duke University (NIH-funded trial) and University of Alabama at Birmingham NIH-funded Nutrition Obesity Research Center; mentorship for a junior investigator at the University of Nebraska–Lincoln who received an NIH-supported training grant; and participation in a Bray Course Planning Committee. O.T.C. declares a research grant from Eli Lilly and Company to his institution to perform the work described in this paper and research grants from NIH and Nestle, Inc., and has served on advisory boards for Novo Nordisk. D.A.K. declares clinical trial and research support from Eli Lilly and Company to his institution to perform the work described in this paper, as well as research support from the NIH. R.V.C. declares clinical trial support from Eli Lilly and Company and research support from Adipo Therapeutics. R.D.M. declares research grants from Grain Foods Foundation, Almond Board of California and Eli Lilly and Company; consulting fees from Mars Foods, General Mills Bright Seed and the Calorie Control Council; honoraria from Clean Label Conference, Columbia University, Sports Nutrition Plus, USDA, Michigan State University, American Diabetes Association, Mediterranean Diet Roundtable, American Society for Nutrition, American Italian Food Coalition and Healthy Aging Science Forum; participation on safety monitoring boards/advisory boards for NIDCD; and presidency of the American Society for Nutrition. U.D. declares a research grant from Eli Lilly and Company to her institution to perform the work described in this paper and research support from the NIH and the International Manganese Institute. S.C. declares payments to her institution to support the work described in this paper. S.S., H.N., A.K., S.U., L.B., E.P., A.H., M.M., D.O.S., Z.M. and T.C. are employees and shareholders of Eli Lilly and Company. D.S. declares no competing interests.