Drinking Water for Weight Loss

Drinking adequate amounts of fluid is an important aspect of a healthy diet. 

In previous work, my former colleagues Michael Boschmann and Jens Jordan in Berlin demonstrated that in healthy men, drinking of 500 ml of water, but not an equal amount of iso-osmotic saline, increases metabolic rate by around 25% for about 60 mins after ingestion (JCEM 2007).

So, can drinking water help with weight management? And, is such an effect specific to water?

This question was now assessed by Jodi Stookey and colleagues from the Oakland Research Institute, Oakland, California, published in this month’s issue of OBESITY.

This retrospective study tested for associations between absolute and relative increases in drinking water and weight loss over 12 months in 173 premenopausal overweight women (aged 25-50 years) undergoing the Stanford A TO Z Weight Loss Study who reported <1 l/day drinking water at baseline.

Diet, physical activity, body weight, percent body fat (dual-energy X-ray absorptiometry), and waist circumference were assessed at baseline, 2, 6, and 12 months. At each time point, mean daily intakes of drinking water, noncaloric, unsweetened caloric (e.g., 100% fruit juice, milk) and sweetened caloric beverages, and food energy and nutrients were estimated using three unannounced 24-h diet recalls. Beverage intake was expressed in absolute (g) and relative terms (% of beverages).

Absolute and relative increases in drinking water were associated with significant loss of body weight and fat over time, independent of diet group, and changes in other beverage intake, the amount and composition of foods consumed and physical activity.

The results suggest that drinking water (but not other fluids, including fluids with artificial sweeteners) may promote weight loss in overweight dieting women.

How important is this finding? It is certainly consistent with the hypothesis that drinking water does indeed affect metabolism. On the other hand – retrospective analyses are fraught with difficulties – guess we’ll need to wait for a prospective randomised controlled trial on this one.

Edmonton, Alberta