Starting an exercise routine doesn’t guarantee that you’ll lose weight, but a lot of us add exercise into our routines when we have a weight loss goal. Read on, and I’ll explain what you really need to know about exercise for weight loss—what kind, how much, and whether it even matters at all.
Yes, exercise (sort of) helps you lose weight
There’s a cliché in the fitness world that the best weight-loss exercises are “fork putdowns and plate pushaways.” I hate when people turn fitness goals into restrictive eating goals, so this framing irritates me, but there is a grain of truth to it.
The true part is that your body weight is determined by both how much activity you do and how much you eat. You need to pay attention to both sides of the equation if you want predictable results. So if you just add exercise, without changing how you eat, you might end up eating more without realizing it, and thus stay the same weight.
But that’s only part of the picture. Technically, you can lose weight just by eating less food, without adding exercise at all. But is that a good idea? Not at all. Exercise is good for us, in terms of heart health, mental health, ability to stay functional as you age, and a hundred more reasons. Those benefits apply whether we’re losing weight or not.
How exercise helps you to eat healthier
Ultimately, the role of exercise in weight loss isn’t (just) to make the weight loss happen, but to keep you healthier while you’re losing weight. That includes maintaining muscle mass and improving heart health, both of which I’ll talk about in a moment. But there’s more: An under-appreciated aspect of exercise is that the more you do it, the more you set yourself up for a healthier diet, a less restrictive attitude toward eating, and better energy levels.
Let’s say we have a pair of twins who don’t exercise much, and they each burn about 2,000 calories a day. One decides to lose weight by eating 1,500 calories, changing nothing else. The other adds enough exercise each day to burn about 500 calories, and thus gets to continue eating 2,000. Both twins are now in a 500 calorie deficit, and should lose about a pound a week. Same thing, right? Not quite.
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Who’s going to have more room in their diet to eat more protein, fiber, healthy fats, vitamins, and minerals? The person who’s eating 2,000.
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Who’s more likely to be able to have their favorite dessert from time to time, instead of cutting it out for the length of the diet? The person who’s eating 2,000.
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Who’s going to be able to eat more carbs, thus fueling themselves better for whatever amount of exercise that they end up doing? The person who’s eating 2,000.
So because both twins are using the same 500-calorie deficit, by the numbers you could say these approaches are equivalent. But the people taking these two approaches will have drastically different experiences.
The most important type of exercise for weight loss: strength training
If you can only do one type of exercise while you try to lose weight, I’d argue it shouldn’t be anything to do with calorie burn at all. It should be strength training.
This includes any type of exercise where the goal is to build strength and muscle. Lifting weights in a gym is the most straightforward example, but you can do strength building exercises with other types of equipment or, in some cases, with no equipment at all. I have a list here of 12 bodyweight exercises that will actually build strength, once you get strong enough that the basics like pushups and air squats get too easy. In general, if you can do more than 15 of something before your muscles fatigue, you should move on to a heavier weight or a harder exercise.
This is because we don’t just want to work on endurance (that’s not the point of strength training). It’s because we want to convince our bodies to build muscle—or at least to hold on to the muscle we already have.
When we lose weight, we’re usually hoping to lose fat, but muscle often goes along with it. Losing muscle means we’re more likely to regain the weight lost. It also means we’ll have a harder time doing other types of exercise; better to run on strong legs than weak legs. And it can also make us weaker when it comes to everyday activities. Muscle loss is a huge problem for older adults, but strength training can slow or reverse it.
How much strength training to do when losing weight:
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Train twice a week, minimum.
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Try to work every body part, including upper and lower body muscles, with pushing and pulling motions.
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Aim for a minimum of three sets of each exercise, with anywhere between 5 and 15 reps per set. By the end you should feel like you can’t do any more (or that maybe you could have done one or two more reps, tops).
These rules of thumb match the general exercise guidelines we should all be following anyway. If you enjoy strength training and want to do more, that’s great! The guidelines are just a minimum.
The second most important type of exercise for weight loss: low to medium intensity cardio
As we saw in our example with the twins, exercise can burn enough calories to increase our overall calorie budget. And even though technically exercise isn’t necessary to create a calorie deficit, it sure seems to help.
Research shows that people who exercise regularly have an easier time losing weight, and an easier time keeping the weight off, than people who don’t exercise. For example, this study had people burn 400 or 600 calories per supervised cardio session, five times a week, but didn’t restrict their diet or give them any diet advice at all. Most of the participants lost weight, averaging about 10 pounds lost at the end of 10 months. By contrast, non-exercising controls, on average, finished the study within about a pound of where they started.
That said: Burning that many calories, five days a week, is a lot of time and work. We’re talking somewhere in the ballpark of 45 to 60 minutes per day, at a low to medium intensity (that study had people at 70-80% of their max heart rate, or in terms of heart rate zones, roughly zones 2 and 3).
Low and moderate intensity exercise makes the most sense for weight loss because it doesn’t cause a lot of fatigue (so you can do plenty of exercise without feeling too tired) and it tends not to spike hunger as much as intense exercise. If you’re a beginner, walking can count as cardio. As you get fitter, you may want to switch to jogging or another exercise like cycling.
How much low and medium intensity cardio to do when losing weight:
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Start with a little more than whatever you’re doing now, and increase from there.
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First try to hit the guidelines of 150 minutes/week (about 30 minutes, five times a week) and then see if you can ramp up to 300 minutes/week (about an hour, five times a week).
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If you can’t hit those specific numbers, do what you reasonably can.
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Aim for “zone 2-3” intensity. It should feel like work, but not torture. The thought of working at that intensity for 45 minutes should inspire a sense of “OK, let’s get this done,” not “oh my god, I’m going to die.”
This low-intensity exercise doesn’t have to be the only exercise you do. If you’d like to run some fast intervals, or play a sport, or take a power yoga class, or anything outside of these recommendations, go for it! Just remember that the low-intensity stuff is a powerful tool for burning calories while keeping your energy up and not feeling excessively hungry.
The worst type of exercise for weight loss: HIIT
I’m going to say something that will sound controversial here, although I don’t think many legit fitness professionals would disagree. HIIT is overrated.
HIIT refers to high-intensity interval training, which can be a time-efficient way of improving your aerobic fitness, at least in the short term. It’s a cool concept, but the name HIIT has been slapped on all kinds of workouts that aren’t really HIIT. Even if you’re doing “real” HIIT, it’s not a magic bullet for weight loss, and shouldn’t be the bulk of your training.
HIIT is basically the opposite of the low intensity cardio I talked about above. HIIT is too fatiguing to do for more than a very short workout, and you probably won’t want to do it every day. If you’re doing a ton of HIIT and wondering why you feel exhausted, that’s why. It also tends to make some people hungrier, which counteracts the calorie-burning benefits. (That said, people react differently to this, so feel free to try it and see whether hunger is an issue for you or not.)
What’s worse, you might be so fatigued from HIIT, or so sore from a session of fake-HIIT, that you end up skipping your strength training workouts. So not only is HIIT a less effective form of cardio, it can also stop you from getting in some of those other important workouts.
All that said: You can do some HIIT if you enjoy HIIT or if you’re interested in the aerobic benefits. Just don’t make it your bread-and-butter. Runners often use an 80/20 rule: 80% of your workouts should be easy intensity; the other 20% can include harder stuff. And no, HIIT isn’t going to spike your cortisol, at least not in a bad way. That’s a whole ’nother myth.
