Grapes themselves do not actually burn fat and just eating grapes will not cause fat cells to go away. While it’s not unusual for fad diets to proclaim they’ve found the ultimate way to lose weight by eating foods that have some special fat-burning capability, the American Heart Association states that it considers the idea of “fat-burning foods” to be “unsubstantiated myths.”
Low Calorie Load
Grapes are relatively low in calories -- 1.5 cups will set you back only about 90 calories -- and they have a high water content, about 80 percent water, according to the Centers for Disease Control and Prevention. If you substitute them for a higher-calorie snack while trying to lose weight, they may appear to burn fat if you end up losing more weight than you had been previously. This can prompt some well-meaning websites to label grapes as a "fat-burning food" as a way to encourage you to eat healthier, but that assertion can lead to misunderstandings if you don’t know the reasons behind the wording.
Polyphenol Research
Another issue is that of polyphenols, beneficial compounds found in fruits like grapes and berries. Research presented at the 2011 meeting of the American Society for Nutrition showed that the polyphenols in blueberries prevented as-yet-unspecialized cells from turning into fat cells in mice. However, this research was on animals only, not humans. Some research shows that another polyphenol, resveratrol, which is found in red grapes, might affect blood sugar levels and fat cell formation, but this research has focused on the resveratrol in wine or isolated compounds, and not the original fruit.
Resveratrol Sources
A 2010 study in the American Journal of Clinical Nutrition found resveratrol itself could possibly prevent general cells from being turned into fat cells. This was not tested in live animals or humans, however; the work was done on cells in a lab. Thus, while the result is promising, it is nowhere near stating that eating grapes will burn off fat. Another study in the same issue of the journal reported that drinking red wine preserved blood sugar levels in subjects, and Science News notes this could have some implications for the treatment of metabolic syndrome. However, drinking red wine made from grapes grown for wine production is not the same as eating table grapes that might not even be red; resveratrol levels could vary between varieties of grapes. Science News also points out that just because resveratrol might stop fat cells from forming does not mean it will destroy existing fat cells.
Normal Effects
Keep in mind that grapes do have calories, no matter how small the amount, and eating enough of even the healthiest food on the planet can take you over your planned caloric intake for the day if you aren’t paying attention. Eat grapes in moderation and stop eating when you’re full instead of worrying about how much of your fat will be gone by morning. Speak to a registered dietitian to develop a healthy eating plan that keeps you well supplied with grapes.
References
- Oklahoma Cooperative Extension Service: Fat and Calories: They Both Count
- American Heart Association: Quick-Weight-Loss or Fad Diets
- Missouri State University: Polyphenols in Grape Berries
- American Journal of Clinical Nutrition: Red Wine Consumption Improves in Vitro Migration of Endothelial Progenitor Cells in Young, Healthy Individuals; S. Hamed et al.
- American Journal of Clinical Nutrition: Resveratrol Regulates Human Adipocyte Number and Function in a Sirt1-Dependent Manner; P Fischer-Posovszky et al.
- West Virginia University: Ask the Expert
- Science Daily: Blueberries May Inhibit Development of Fat Cells
- Science News: How Resveratrol (in Grapes, Peanuts and Wine) Fights Fat and Disease
- Centers for Disease Control and Prevention: Fruit of the Month - Grapes
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