We all know that drinking water is vital to our health. Water is an essential component of innumerable biological processes. And, we know that consuming water is key when we exercise, because we lose fluid as we sweat.
Conventional wisdom has led us to believe that water consumption can have nearly unlimited health benefits. One of these supposed “benefits” is the belief that drinking more water will decrease hunger and thus calorie intake. Even health professionals advocate increasing water consumption. However, there has been limited scientific evidence to support this practice.
Only a couple of studies to date have specifically examined the effects of drinking more water on weight. Most of the literature has focused instead on healthy diet alterations like replacing sugar-sweetened (i.e., high calorie) beverages with water. On that topic, at least, scientists agree that trading up to water decreases the number of calories eaten at meals.
In September, a group of researchers from the University of Birmingham in England published a study showing that preloading with water before meals can enhance weight loss. The study has attracted attention particularly from nutrition and fitness publications. However, many of these articles are incomplete or even misleading. So, we at D21 want to clarify this intriguing research for our readers.
PARTICIPANTS WHO PRELOADED WATER THREE TIMES A DAY LOST AN AVERAGE OF 9.5 LBS IN 3 MONTHS.
The study focused specifically on weight changes in the obese. Participants were instructed to drink 500mL of water (a little more than 16oz), 30 minutes before each main meal. The researchers then measured the change in participants’ weight from the beginning of the study to the end – three months later.
The scientists found that those who preloaded water lost more weight (about 5 lbs) than the control group (about 2.5 lbs) who were instead instructed to imagine that their stomachs were full before meals. The team also noted that some participants occasionally forgot to preload before a meal, and that the amount of weight loss was greatest (nearly 9.5 lbs) in those who consistently preloaded before all three main meals.
WATER PRELOADING MAY REPRESENT A LOW RISK, HIGHLY ACCESSIBLE, EASILY MAINTAINED, AND BASICALLY FREE STRATEGY FOR WEIGHT LOSS.
As with any study, important questions remain. For instance, is this weight change brief, and then gained back, or is the weight loss maintained? Future studies which follow participants for longer than three months, perhaps a year, would help answer this question.
The researchers also pointed out that scientists still don’t understand exactly why increasing water consumption affects weight. For example, in this study, the participants in the preloading and control groups reported no significant differences in feelings of fullness (the feeling that your stomach is physically full) and satiety (the feeling of being satisfied or not hungry).
Although more research is clearly needed, this study is very encouraging. The authors pointed out that the beauty of water preloading is that it may represent a low risk, highly accessible, easily maintained, and essentially a free strategy for weight loss. Now, that’s a plan we can all get behind!
So, if you are interested in trying water preloading as part of your diet and exercise plan for weight loss, here are a few tips:
* Consume about two 8oz glasses of water 30 minutes before eating each main meal.
* Drink only still water. Avoid carbonated, mineral, or sparkling waters; these affect the stomach differently from still water.
* Drink water that has NO caffeine, sugar, or substitute sweeteners. Caffeine is a well-known diuretic, sugar contains calories, and substitute sweeteners haven’t been sufficiently studied in this context.
* Water with a little natural flavor like lemon or mint is probably fine!
Lastly, always confer with your physician or nutritionist before making a significant change to your diet. Certain health conditions may not be compatible with water preloading. Your health professional will also be able to give you guidance about measuring changes in weight.
References & Resources
1. Paretti et al. (2015) Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT. Obesity
The contents of this article & website are for educational purposes and are not intended to offer individualized medical advice. You should seek the advice of your physician or other qualified health professional with any questions you may have about medical conditions. Always adhere to advice given to you by a medical professional, even if it is different from information provided on this website.