Does drinking water before meals really promote weight loss?

If you’ve ever tried to lose excess weight, you’ve probably received this advice: drink more water. Or perhaps it was more specific: drink a full glass of water before each meal. The second suggestion seems like a reasonable idea, right? If you fill your stomach with water before eating, you’ll feel fuller and stop eating sooner.

But did that work for you? Would drinking more water throughout the day work? Why do people say drinking water can help with weight loss — and what does the evidence show? Top theories include: Feel full, eat less. As noted, filling up on water before meals has intuitive appeal. Your stomach has nerves that sense stretch and send signals to the brain that it’s time to stop eating.

Presumably, drinking before a meal could send similar signals. The evidence: Some small, short-term studies support this idea. For example, older study subjects who drank a full glass of water before meals tended to eat less than those who didn’t.

Another study found that people following a low-calorie diet who drank extra water before meals had less appetite and more weight loss over 12 weeks than those on a similar diet without the extra water. But neither study assessed the impact of drinking extra water on long-term weight loss. Burning off calories.

The water we drink must be heated up to body temperature, a process requiring the body to expend energy. The energy spent on this — called thermogenesis — could offset calories from meals. The evidence: Thou.