In January 2019 I decided that I would try to exercise for 60 minutes each day. My workouts could be anything and any intensity. And for most of the year, I have been able to keep this goal for at least five days a week. As a result, I have lost about 8 pounds without changing my eating.
So in another not surprising research moment, a new study found that people who exercise for 300 minutes per week lost weight. Apparently I had stumbled on an easy weight loss strategy without knowing it. Exercise and weight loss have never been a match made in heaven.
Past studies examining exercise’s effect on weight loss has found that exercise usually doesn’t cause significant weight loss, if any at all. That is because, usually people eat more calories to make up the calories they burned. In fact, in some cases, people would gain weight.
But this new study published in Medicine & Science in Sports & Exercise is different. It found that those who exercised 40-60 minutes a day, six days a week, lost weight exercising. Here’s why.
First thing to know is that this study follows up on 2018 study done by the researchers. In that study, they wanted to explore whether there was a ceiling to how many calories people would consume after exercise. Researchers had participants burn either 1,500 or 3,000 calories a week to see if there was a high point of calories consumed to compensate for calories burned.
There was, and that number was 1,000. No matter whether the participants burned 1,500 or 3,000 calories they ate 1,000 more calories. So those who exercised more lost more weight. The take-home: The more time exercising, the more calories burned per week, the more deficit created, and the more weight lost.
Now, this latest study builds upon the 2018 finding by mostly recreating it. Again, those who worked out the most, lost the most weight. But this time, the researchers discovered that 300-minutes-per-week workout group experienced changes in their appetite hormones; specifically, the levels of leptin—the hormone that can reduce appetite. What does this mean? The more exercise increased the exercisers’ sensitivity to the hormone, enabling them to better regulate their desire to eat. Those who didn’t exercised less didn’t experience this.
Together this pair of studies show how exercise can help people lose weight. We know that we will eat to compensate for our activity because that’s just how we are evolutionarily built, but now we know that there is an upper threshold of how much we’ll eat. So, more exercise not only creates a deficit but changes our appetite. All things that I can attest to. In some ways I feel like I am living science.