Why Do I Gain Weight When I Try to Lose It?

If you’ve been trying to lose weight by cutting calories and exercising regularly, but aren’t seeing the results you were hoping for, or your progress has stalled, then we’ve got just the man to help you.

About Our Expert
About Our Expert
Dr Nick Knight

Dr Nick Knight is a doctor in a London hospital, with a degree in exercise and sports sciences and a PhD in human performance. Dr Knight has trained a four-man crew to row 5,000km across the Indian Ocean and has carried out medical research at Mount Everest Base Camp.

Dr Nick Knight has dispensed concise advice to Coach readers on all kinds of medical topics you may have been wondering about, from back pain to ball-ache. He’s explained the difference between a strain and a sprain and enlightened us on how to stop snoring. Here, Knight explains why you may not be losing weight as quickly as you’d like to, and why you may be doing everything right.

“Losing weight can be a complicated business,” says Knight. “In the first week of your exercise regime and calorie restriction you may find that you lose weight quickly. There's a reason for that. As you drop carbohydrates from your stores within your liver and muscles, you lose water – for every gram of carbohydrate, you lose two grams of water. Then you might find your weight plateaus and even goes up.” 

But why? “As you exercise you will lose fat from your body,” says Knight, “but conversely, you will gain muscle through training. Muscle is 80% denser than fat. And that's why your weight stabilises.”

So don’t lose heart: you’re building muscle as you lose fat, and that’s a good thing. As we discovered when we spoke to Michael Gleeson, an expert in exercise biochemistry, about metabolism and weight loss, maintaining or even increasing your muscle mass can combat your body’s metabolism slowing down in response to fewer calories.

If you want to be reassured, you can track your muscle mass on a smart scale. You’ll find models for as little as £30 in our round-up of the best smart scales

And to help make sure you’re doing all the right things, read our expert guide to the best exercises for weight loss, these weight loss tips from dietitians, and consider following our fat loss meal plan for men or weight loss meal plan for women to ensure your body gets the recommended amounts of nutrients every week while reducing the calories.

Craft beer drinker, Devonian, fisherman and former content director of Coach online, Chris contributed style coverage and features between 2016 and 2019.