Many of you have seen the article in The New York Times, “To Lose Weight with Exercise, Aim for 300 Minutes a Week,” by Gretchen Reynolds. It appeared on December 9, and it caught my eye. Here is the link: https://www.nytimes.com/2020/12/09/well/move/to-lose-weight-with-exercise-aim-for-300-minutes-a-week.html.
For a long time, the fitness industry has professed that adults (of any age) should be engaged in exercise (cardio or resistance) for 150 minutes per week. There have been many times when I have started working with new clients who have been sedentary; I get a blank stare at mentioning two-and-a-half hours each week. “Wouldn’t our weekly 30 minutes be enough?” I have to start them slowly and encourage them to add workouts even when they are not with me until they get to the recommended level.
So what’s with the new 300 number? Reynolds reports that 300 minutes per week has now been shown to assist in weight loss, which is not necessarily the goal for everyone–thus the distinction between 150 and 300. When clients talk to me about weight loss strategies, I emphasize diet. Exercise helps (except when it does not), but lowering calorie intake is the best way to ensure weight loss. The problem with exercise is that when we work out, our body in turn often demands more calories; our appetites increase and the added eating erases any of the gains from working out.
The study cited in the article points out that people who exercise will consume more “compensatory calories;” usually this amounts to 1000 calories per week. So if a person burns 1500 calories at the gym in a week, we can expect that person to eat an extra 1000, leading to a deficit of only 500 calories. One pound of fat in the human body is about 3500 calories; at this rate, a person would lose one pound every 7 weeks. The new research shows that those who exercise 300 minutes per week will average closer to 3000 calories burned from that activity; subtract the 1000 in compensatory calories and it is still a deficit of 2000 calories. In this scenario, a pound would be lost every two weeks or so–certainly a healthy pace. Additionally, those working out at the higher rate had an increase in the hormone leptin which controls appetite.
This research is certainly helpful, but I am not sure whether it will have huge implications. Folks who are sedentary, obese, or have other health problems will have a hard time scaling up to 150 minutes per week, let alone 300. Controlling one’s calorie intake (together with exercise) still seems a reasonable approach. The best course of action, as always, is to build a healthy lifestyle including: healthier eating, exercise, rest, low alcohol consumption, and no smoking. This is recommended not just for 300 hours/week…but every hour of every day.