Expert Q&A

Water weight loss: What causes it?

Can you explain why so many diets cause water weight loss rather than true weight loss? Also, what steps can I take to avoid losing water weight? -Emily from Georgia

On a low-carbohydrate, high-protein diet, the initial weight loss is caused by your body’s release of extra water. This happens because carbohydrates and glucose are your body’s preferred energy source. In the absence of these nutrients, your body breaks down glycogen for energy. This metabolic process increases the amount of water you lose. However, when your body uses all its glycogen reserves, it’ll eventually start burning fat. At this point, your weight loss slows down and water weight loss tapers off.

True sustainable weight loss comes from increasing your energy output and reducing the amount you take in. If you cut 3,500 calories from your diet per week, this equates to roughly 1 pound of fat loss. One pound per week is the safe, recommended weight loss rate.

To achieve this rate of weight loss, aim to run a 500 “calorie-deficit” each day. You can achieve this deficit by eating less and/or exercising more on a consistent basis over a long period of time. A healthy weight loss strategy combines regular exercise with a well-balanced diet to run a daily calorie deficit of 500 calories. This way, you will lose fat, not water weight.

Katie Clark, MPH, RD
Contributing Expert

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