Raspberries and other red berries may assist with weight loss.

Berries like raspberries have many health benefits and they are a delicious part of any diet. In recent years, many supplement companies have marketed raspberry ketones as a cure for weight loss, but why eat a pill or capsule when the fruit may do the same with fewer side effects. The chemicals in berries are poorly understood but there is growing research to support the health claims. However, berries and select phytochemicals present in berries have been poorly studied.

A study from 2016 looked at raspberries and phytochemicals​[1]​. This study tested the relative effect of whole raspberry products or raspberry phytochemicals using mice fed a high-fat, high-sucrose diet as a model similar to the Western diet. The development of obesity and related metabolic complications were measured. The mice were fed experimental diets for ten weeks. Diets were formulated to include a typical dietary level of whole raspberry food products that were high in these phytochemicals. In week nine, a glucose tolerance test was conducted.

The researchers found that the addition of raspberry food products and phytochemicals to the high-fat diet reduced body weight gain significantly when raspberry juice and puree concentrates were added. Food efficiency values reflected these weight changes, with the same three groups having food efficiencies similar to normal-weighted low-fat-fed mice. Eating the equivalent of one serving of red raspberries every day curbed weight gain in mice even when they ate an unhealthy, high-fat diet. Although the study was performed in mice, human and mice metabolism is similar, and results in humans are not expected to be different.

The mice also had lower indicators of metabolic syndrome and diabetes. These conditions are both tied to obesity and weight gain through insulin resistance. The active ingredient in raspberries is also found in cranberries, cherries, and strawberries. Red fruits contain anthocyanins and flavonoids that may increase energy production and decrease fat absorption. No matter if it is the phytochemicals or fiber, these red berries appear to help with weight loss.

The bottom line: Raspberries are not only tasted great but they may also help you lose weight. When added to a high-fat diet, raspberry juice and puree concentrates decreased weight gain despite the consumption of a high-fat diet. More research is needed, but these results are promising.