New research presented at the 2025 American Physiology Summit suggests that tomatoes—and more specifically, the red pigment lycopene found in them—may help protect the liver and prevent weight gain, even when eating a high-fat diet.
Lycopene is a natural compound that gives tomatoes and watermelons their bright red color. It is also a powerful antioxidant that helps reduce inflammation in the body.
This study, led by Dr. Samantha St. Clair, a biology professor at Northern State University, explored whether tomatoes could help reduce the risk of obesity. The team was inspired by earlier research showing that estrogen supplements protected overfed zebrafish from gaining too much weight.
Because lycopene and other tomato compounds affect some of the same chemical processes in the body as estrogen does, the scientists wanted to find out if tomatoes could offer similar protection.
To test this idea, researchers used zebrafish—a common model for studying metabolism—and fed them a high-fat diet along with different combinations of tomato extract, lycopene supplements, and estrogen. They also had a control group of fish eating a normal diet without extra fat or supplements.
The results were surprising. Zebrafish on a high-fat diet that received tomato extract gained less weight than those given estrogen supplements alone.
Even more interesting, fish that ate a high-fat diet with both lycopene and estrogen had lower blood sugar levels than fish on a regular diet. This suggests that lycopene helps the liver break down fat more effectively, which in turn supports better blood sugar control.
What’s especially encouraging is that the benefits of tomato consumption showed up quickly. The researchers saw noticeable improvements in metabolism after just one week. According to Dr. St. Clair, “If a relatively short-term change in diet can help prevent weight gain, this means people might be able to see real results from small changes in just a few weeks.”
The study also showed that the benefits of tomatoes and lycopene may come from their ability to reduce inflammation in the liver. Inflammation is a key factor in many health problems, including obesity, fatty liver disease, and type 2 diabetes. By calming this inflammation, lycopene may help the liver function more efficiently.
The researchers are now digging deeper to understand how tomatoes and lycopene work on a genetic level. They are studying changes in liver genes that control inflammation, fat breakdown, and hormone processing. They also plan to compare different kinds of tomatoes to see if some varieties have more lycopene or stronger health effects than others.
Although lycopene is available as a supplement, the researchers caution that these products are not closely monitored by the U.S. Food and Drug Administration, and their effects in humans are not fully understood. Eating tomatoes or tomato-based foods like sauces, soups, or juices may be a safer and more natural way to gain the benefits.
In summary, this study offers promising news: adding more tomatoes to your diet could help protect your liver, manage blood sugar, and prevent weight gain—especially if your diet is high in fat. While more research is needed to confirm the findings in humans, this is another reason to enjoy a fresh tomato salad or a bowl of tomato soup as part of a healthy lifestyle.
If you care about weight management, please read studies about diets that could boost your gut health and weight loss, and 10 small changes you can make today to prevent weight gain.
For more health information, please see recent studies about low-carb keto diet could manage obesity effectively and results showing popular weight loss diet linked to heart disease and cancer.
The research findings can be found in European Heart Journal.
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