Though red meat is packed with protein, a nutrient shown to aid weight loss it’s also a rich source of iron. This mineral, when consumed in excess, can increase the risk of weight gain and disease, according to a Journal of Clinical Investigation study. The Wake Forest Baptist Medical Center researchers behind the report say that consuming too much iron suppresses leptin, an appetite-suppressing hormone that tells the brain when we’ve eaten our fill. In short: When leptin levels are low, we’re left with a monster appetite that causes us to overeat.
In the study, researchers divided male mice into two groups: One group was given a high-iron diet (2000 mg/kg) while the other group was fed a low-to-normal-iron diet (35 mg/kg). After two months, researchers measured the levels of iron in animals’ fat tissue. Since excess iron cannot be excreted, a 215 percent increase of iron was observed in the high-iron group as were severely diminished leptin levels. In turn, these animals’ food intake was also much greater.
And that translates to a whole host of negative consequences in humans: "In people, high iron… has been implicated as a contributing factor to many diseases, including diabetes, fatty liver disease and Alzheimer's, so this is yet another reason not to eat so much red meat,” Don McClain, M.D., Ph.D., senior author of the study said in a statement. "We don't know yet what optimal iron tissue level is, but we are hoping to do a large clinical trial to determine if decreasing iron levels has any effect on weight and diabetes risk," he adds.
Eat This! Tip
Consume no more than two or three servings (each about 3 ounces) of red meat per week, and stick to lean and grass-fed varieties whenever possible. Grass-fed meat naturally has fewer calories than conventional meat and contains higher levels of omega-3 fatty acids. Omega-3s have been shown to reduce inflammation, improve insulin resistance and help the liver carry fat out of the body, so it’s the best bet for your waistline.