A few studies indicate that drinking coffee or tea with caffeine may slightly boost weight loss or prevent weight gain. But there’s no evidence that increased caffeine consumption results in significant or permanent weight loss. And some of the studies looking at caffeine and weight were poor quality or done on animals, making the results questionable or hard to generalize to humans. In addition, some studies found that decaffeinated coffee may contribute to modest changes in weight, suggesting that substances or factors besides caffeine may play a role in weight loss.

Although the research about caffeine and weight isn’t definitive, researchers have several theories about how caffeine affects weight:

• Appetite suppression. Caffeine may reduce your desire to eat for a brief time, but there’s not enough evidence to show that long-term consumption aids weight loss.
• Calorie burning. Caffeine may stimulate thermogenesis — one way your body generates heat and energy from digesting food. But this probably isn’t enough to produce significant weight loss.
• Water loss. Caffeine acts as a diuretic, which means it increases the amount of urine you excrete. This water loss may temporarily decrease your body weight.

While you may be tempted to try caffeine to aid weight loss, keep in mind that caffeine’s a stimulant and too much can cause nervousness, insomnia and other problems. Also, some caffeinated beverages, such as specialty coffees, are high in calories and fat. So instead of losing weight, you might actually gain weight.

Do you drink caffeine?