Can you lose weight just by downing a glass of water before dinner? The idea seems straightforward: You drink water before a meal, your stomach fills up a bit, so you eat less. But does intuition stand up to research?
Dr. Brenda Davy, an associate professor of human nutrition at Virginia Tech, has recently conducted studies on how drinking water relates to weight loss in people middle-aged and older (for which she and her lab group maintain a blog). I got to ask Davy what her research means for those of us looking to slim down: Can timing really have that big of an impact?
JOYNER: What have you found is the optimal amount of water to drink before meals if you're trying to lose weight, and what is the best timing?
DAVY: Very few studies have directly addressed this issue. But we have studied this—and found that when middle-aged and older adults drink two cups of water approximately 15–20 minutes before consuming each of their three main daily meals, they eat about 75–90 fewer calories at the meal. When they do this water-appetizer routine daily for three months, while also trying to cut back on their calorie intake, weight loss occurs. Our comparison group lost about 11 pounds, while our water-appetizer group lost close to 16 pounds over three months on average. So the water regimen appeared to facilitate weight loss.
How do your studies of subjects with higher BMIs translate to fitter people who want to drop a few pounds or manage their weight when they can’t train as much as they'd prefer?
We conducted the test-meal water-appetizer studies in both normal weight and overweight/obese adults. Both groups reported feeling more full and less hungry after the water appetizer, and as a result, they ate fewer calories at the meal. So this approach may work for middle-aged and older adults regardless of their weight status.
Have the studies left you with any pressing questions?
One thing we don’t yet know is if this strategy works in younger folks–who tend to drink a lot of sugary drinks. Even beverages that many people think are healthy, such as Vitaminwater or sports drinks, have calories and added sugar. Water is the best option, in most cases. And many older adults don’t drink enough water. The Institute of Medicine recommends about 9 cups per day for women and about 13 cups per day for men. In contrast, usual drinking water intake in the U.S. is about four cups per day.
Are there any other benefits to drinking water that with weight loss?
In addition to the positive effects on food consumption and hunger, acute water consumption also causes resting metabolic rate to increase by about 30 percent. Eat a bit less and burn a few more calories, and it adds up over time.
All of this points to some pretty straightforward advice:
- Drink a glass of water before meals.
- Avoid routine consumption of sugar-sweetened beverages (SSBs) (which have contributed significantly to the obesity epidemic). I'm all for sports drinks when it comes to delaying fatigue and improving performance, but they're only necessary during intense physical training and competition of an hour or longer. Water is your best bet under just about all other circumstances.
Michael J. Joyner, M.D., is a physiologist and anesthesiologist at the Mayo Clinic and a leading voice in the world of exercise physiology. Over the past 25-plus years, he's published hundreds of studies, many of which have focused on how humans respond to exercise. Dr. Joyner also writes at Human Limits. The views expressed in his posts are his own and do not reflect those of his employer.