In a new study, researchers found that an experimental antibody drug that targets one of the body’s key metabolism regulators may help obese people lose weight.
The injection drug mimics the effects of a natural hormone called fibroblast growth factor 21 (FGF21). In the body, FGF21 helps govern metabolism, calorie-burning and food intake.
The researchers found that a single injection spurred “metabolic improvements” in overweight and obese adults that lasted up to two months.
On average, people started eating fewer calories after a week and saw their “good” HDL cholesterol increase while their levels of “bad” LDL cholesterol, insulin, and triglycerides all fell.
Beyond that, their food preferences started to shift away from sweets, and they managed to drop a couple of pounds—albeit temporarily.
The research was conducted by a team at Genentech Research and Early Development, Genentech, Inc., South San Francisco.
FGF21 is a hormone that helps control metabolism by stimulating certain receptors in fat tissue, the liver, the pancreas and the central nervous system.
Previous research has suggested that people who carry certain variants in the FGF21 gene tend to have a sweet tooth and a preference for carbohydrates.
In addition, people with obesity, type 2 diabetes or non-alcoholic fatty liver disease appear to have high levels of FGF21 in their blood.
That suggests they may have grown resistant to the hormone—similar to how people become resistant to insulin.
Scientists have tried giving modified versions of FGF21 to benefit metabolism. But the protein is cleared from the body too quickly to be useful.
In the study, the team developed a lab-engineered antibody that essentially mimics the hormone.
As an initial test, they recruited 60 overweight and obese adults, then randomly assigned them to have a single injection of the antibody or a placebo.
For about a week, the participants stayed at the research center, following a controlled diet.
And by the end of that week, people given the antibody drug had lost more weight than the placebo group—about 2 pounds more, on average.
Once the participants went home, the weight quickly returned. However, improvements in cholesterol, triglycerides, and blood sugar were more sustained.
They also showed a lasting increase in a hormone called adiponectin, Arora said. Adiponectin helps regulate blood sugar and fatty acid breakdown.
To the team, the promise of the antibody drug is not really in weight loss—but as a possible treatment for metabolic conditions that are often related to obesity.
For example, non-alcoholic fatty liver disease, where—for unknown reasons—fat builds up in the liver, sometimes leading to cirrhosis. FGF21 seems to clear fat from the liver.
The researchers also suggest that stimulating FGF21 receptors may dampen people’s appetites not only for sweets but for alcohol. If such effects hold up, Arora said, that could aid with weight loss.
No major side effects were found in this study. Some people given the antibody developed nausea, diarrhea, or constipation. But the safety and effectiveness of repeat injections over time remain unknown.
One author of the study is Dr. Puneet Arora.
The study is published in PNAS.
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