Lifting, walking and cardio

Lift weights at least two days a week to keep your muscle, and walk every day. A workout burns fewer extra calories than you’d think, because your body makes up some of the difference. Food makes most of the deficit, and movement decides how much of what you lose is fat.

Can you outrun a bad diet?

Picture the usual January plan. Run or go to the gym every day, burn a few hundred extra calories, keep eating the same, and watch the fat come off. By February the gyms are emptier again and the weight is the same.

There’s a second camp that has heard the first one fail and says exercise is useless for weight loss. Both are partly wrong. Exercise does burn calories, just fewer extra calories than the treadmill shows, and it’s the best thing you can do for what your weight is made of.

The hunter-gatherers who burn the same as office workers

The Hadza are hunter-gatherers in northern Tanzania. In 2012 Herman Pontzer and his colleagues measured how much energy 30 Hadza adults burned over 11 days, using a lab method that tracks water labeled with harmless tracers through the body. GPS units showed the women walking about 3.6 miles (5.8 km) a day and the men about 7.1 miles (11.4 km).

After accounting for body size, the Hadza burned about the same number of calories a day as Western adults. They were far more active, and their bodies spent the energy differently, but the total came out the same.

In 2016 Pontzer’s team measured 332 adults across five countries. Daily burn rose with activity at the low end, then levelled off for the most active people. In 2021 a larger team pooled data from 1,754 adults and found that, on average, only 72% of the calories burned in activity showed up as extra calories burned that day. The other 28% were made up elsewhere. In the people with the most bodyfat, it was about 46%.

Your body runs on something like a monthly budget. Add a gym membership and your salary doesn’t go up by the full price. Your body trims some of its other spending to make room.

Does exercise alone work for weight loss?

Exercise works for weight loss, but it’s an expensive way to make a deficit. A smaller change to your food does the same job. Exercise earns its place for what it does for your muscle, heart and blood sugar, and it helps keep weight off once it’s gone.

Why should you lift weights on a diet?

When you eat less, your body takes some of the weight from muscle. In people with overweight or obesity, about 20 to 30% of the weight lost on a diet alone is lean mass. Lifting is the signal that keeps it.

The US activity guidelines ask for at least two days a week of muscle work. Here’s the simplest version of it.

1. Two or three sessions a week. Each one works the whole body.
2. Four kinds of move. A squat or leg press, a hinge like a deadlift or hip thrust, a push like a press or push-up, and a pull like a row or pull-up.
3. A few hard sets of each. Stop each set with a rep or two left in you.
4. A little more over time. Add a rep or a little weight when it gets easy. On a diet, holding your strength steady is a good result.

Machines, dumbbells, bands and bodyweight all count. Protein does the other half of the job, and your number is in your calories, pace and protein. Sleep helps too. In a small trial, the same diet with 5.5 hours of sleep instead of 8.5 took 60% more lean mass.

How much should you walk?

Walking, standing, fidgeting, cooking and carrying shopping are called non-exercise activity. They add up to more than most people think, and they tend to fall when you diet.

The researcher James Levine showed how much they add up. In a 1999 study his team overfed 16 lean adults by 1,000 calories a day for eight weeks. Some gained ten times as much fat as others. About two thirds of the extra calories people burned came from moving more without meaning to, and how much each person’s non-exercise movement rose predicted how little fat they gained.

In 2005 his team fitted 10 lean and 10 mildly obese people with sensors that logged their posture every half second for ten days. The people with obesity sat about two hours a day longer. The team worked out that moving like the lean group would burn about 350 more calories a day.

The CDC asks adults for 150 minutes a week of brisk activity like fast walking. We’d add a daily step habit on top, and the habit to protect is keeping your steps steady while you diet. Why your burn drops explains why that’s the part that slips.

• Walk after meals, even 10 minutes.
• Take phone calls on your feet.
• Walk to anything within about 20 minutes.
• Park at the far end and take the stairs.

Cardio, HIIT and fasted workouts

Pick the cardio you’ll keep doing. It does a lot for your heart, and less for your fat than the machine says.

• HIIT and steady cardio lose about the same fat. A 2017 review of 13 trials in adults with overweight found no difference in fat loss between the two. HIIT took about 40% less time.
• Fasted cardio doesn’t lose more fat. In a four week trial, 20 young women on the same diet did an hour of cardio three times a week, fasted or after a small meal. Both groups lost fat, and the groups didn’t differ.
• You can’t pick where the fat comes off. In a 2011 study, 24 adults did seven ab exercises five days a week for six weeks on their usual food. Their bellies didn’t shrink. Only their sit-up scores improved. More on burning fat from one spot.

Should you eat back your exercise calories?

No. Watch estimates for calories are the least accurate number they show. In a 2017 Stanford test of seven wrist devices in 60 people, heart rate was close, and calories were off by 27% for the best device and 93% for the worst. None got under 20%. A 2025 review of 56 Apple Watch studies found every calorie estimate missed by more than 10%.

Add your body’s 28% of compensation on top and eating back a workout can erase the deficit. Set your calories from your average week and let the scale do the counting, the way tracking your food and your weight lays out.