Exercise for weight loss: where beginners should start

The easiest workout for weight loss is brisk walking, and the best one is whichever you’ll still be doing in six months. Exercise alone takes off a few percent of body weight. Its larger jobs are protecting muscle while you lose weight and helping you keep the weight off afterward. This guide covers where to start, how to build up, and what to skip.

What exercise alone can do for the scale

The American College of Sports Medicine’s position stand (Donnelly et al., Medicine & Science in Sports & Exercise, 2009) reviewed the exercise-only trials. Under 150 minutes a week of moderate activity produced little weight loss. More than 150 minutes produced roughly 2–3 kg, and 225–420 minutes a week produced roughly 5–7.5 kg.

The Midwest Exercise Trial 2 (Donnelly et al., Obesity, 2013, n=141) pushed harder. Adults with overweight or obesity did supervised exercise 5 days a week for 10 months, burning 400 or 600 calories per session, with no diet change. They lost about 4% and 6% of body weight on average. That was five supervised sessions a week for ten months, which is more than most people will keep up on their own.

Compare that with medication. In STEP 1 (Wilding et al., NEJM 2021, n=1,961), brand-name semaglutide (Wegovy) 2.4 mg produced 14.9% average weight loss at 68 weeks, against 2.4% on placebo. In SURMOUNT-1 (Jastreboff et al., NEJM 2022, n=2,539), brand-name tirzepatide (Zepbound) produced up to 20.9% at the 15 mg dose over 72 weeks, against 3.1% on placebo. Both trials paired the drug with diet and activity counseling in both groups.

The gap is mostly arithmetic. A 30-minute brisk walk burns about 133 calories for a 155-lb person, per Harvard Health’s estimates. A cut in how much you eat can remove several times that every day without any time cost. Your body also partly makes up for exercise, through appetite and possibly by moving less the rest of the day. How much varies a lot between people, and it’s hard to measure.

So exercise is a weak tool for losing weight and a strong one for nearly everything else: blood pressure, blood sugar, mood, sleep, strength, and whether the weight stays off.

Exercise helps most with keeping weight off

In a Danish trial (Lundgren et al., NEJM 2021, n=195), adults who had already lost about 12% of their weight on a low-calorie diet were randomized for a year to exercise, liraglutide (an older daily GLP-1), both, or placebo. Compared with placebo, the exercise group kept off about 4 kg more, liraglutide about 7 kg more, and the combination about 9.5 kg more, with the largest drop in body fat. That was liraglutide, not semaglutide or tirzepatide, so it’s a reasonable but untested guide to the newer drugs.

Low-barrier ways to start

If you have obesity, joint pain, or haven’t exercised in years, pick from this list by one test: can you imagine doing it three times next week? Harvard Health’s calorie figures (updated 2021) are given for 30 minutes at 155 lb and 185 lb. They’re rough estimates, and heavier bodies burn more for the same activity.

• Walking. No equipment, no learning curve, and you can split it into 10-minute pieces. Brisk walking at 3.5 mph: about 133 / 159 calories. If your knees complain, flat ground and good shoes come before anything else.
• Cycling, stationary or outdoor. The bike carries your body weight, so it’s easier on knees and hips than walking for many people. Moderate stationary cycling: about 252 / 294 calories. A recumbent bike (the kind with a seat back) helps if your back or balance is a problem.
• Swimming or water aerobics. Water takes most of your weight off your joints, which makes it the kindest option for severe knee or hip arthritis. General swimming: about 216 / 252 calories. Water aerobics: about 144 / 168. You don’t need to know how to swim for water aerobics.
• Bodyweight circuits. Sit-to-stands from a chair, wall or counter push-ups, step-ups on the bottom stair, glute bridges on the floor. Do each for 30–45 seconds, rest, repeat two or three rounds. Moderate calisthenics: about 162 / 189 calories. This one doubles as strength training.
• Yoga. Low calorie burn (hatha yoga: about 144 / 168) but real value for balance, flexibility, and getting comfortable moving again. Chair yoga exists and counts.

Running, HIIT classes, and team sports burn more per minute. They also carry more injury risk for a heavier or deconditioned body, and they’re easier to quit. Treat them as something to build toward if you want to.

Building up to 150 minutes

The US Physical Activity Guidelines (HHS, 2nd edition, 2018) set the target: 150–300 minutes a week of moderate activity, or 75–150 minutes of vigorous activity, plus muscle-strengthening work on at least 2 days. Moderate means you can talk but not sing. The guidelines also state plainly that some activity is better than none, and that any amount counts toward the total.

One workable ramp from zero. Adjust it to your body, your schedule, and your clinician’s advice:

1. Weeks 1–2: 10 minutes a day, 5 days a week. That’s 50 minutes a week. The goal is the habit.
2. Weeks 3–4: 15–20 minutes a day. Add one short strength session.
3. Weeks 5–8: 20–30 minutes a day, 5 days a week, which lands you at 100–150 minutes. Two strength sessions.
4. After that: add time before you add intensity. Going past 150 minutes a week is where the ACSM data show more weight loss.

If something hurts the next day beyond ordinary muscle soreness, drop back a week.

Talk to your clinician before starting if you have heart disease, chest pain or unusual breathlessness on exertion, or diabetes treated with insulin or a sulfonylurea. Exercise lowers blood sugar, and alongside a GLP-1 those medications can push it too low.

How to use a step count

Step counts are the easiest way to measure walking without timing it. The 10,000 figure started as a marketing number, not a research finding.

The better data come from a meta-analysis of 15 cohorts (Paluch et al., Lancet Public Health, 2022, n=47,471). The risk of death fell as steps rose, then leveled off at about 6,000–8,000 steps a day in adults 60 and older, and 8,000–10,000 in younger adults. Those are observational numbers about mortality, not weight, but they’re the best evidence for a daily target.

In practice: check your average over a normal week, then add about 1,000 steps a day and hold that for two weeks before adding more. A 10-minute walk is roughly 1,000 steps for most people.

Strength training matters more on a GLP-1

When you eat much less, your body breaks down some muscle along with fat. On a GLP-1 the drop in intake is large and fast, and DXA substudies (body scans that separate fat from lean tissue) show a real share of the weight lost is lean mass. We don’t yet know what that means for strength and function years later.

The countermeasures are the ones used in every other kind of rapid weight loss: resistance training twice a week and protein around 1.2–1.6 g per kilogram of body weight a day. Neither has been tested in a large GLP-1 trial. The biology points one way, and the cost is about an hour a week.

Strength training doesn’t mean a gym. Bands, dumbbells, and your body weight cover a squat, a hip hinge, a push, and a pull. The full reasoning, with the protein math, is in strength and recovery on a weight-loss plan. If you want an exact twice-a-week program, the men’s workout plan works for anyone, and preventing muscle loss on a GLP-1 covers what to skip.

HIIT or steady cardio

High-intensity interval training alternates short hard efforts with recovery. Its real advantage is time. In a meta-analysis of adults with overweight or obesity (Wewege et al., Obesity Reviews, 2017), HIIT and moderate steady cardio produced similar reductions in body fat, and HIIT got there in less total time.

That’s the whole case. HIIT doesn’t burn meaningfully more fat, and it’s harder to recover from, harder on joints, and harder to stick with for a beginner. If you’re short on time and your joints are fine, intervals on a bike are a reasonable choice. Otherwise, steady walking or cycling does the same job.

Two myths to drop

Sweating burns fat. Sweat is water your body releases to cool down. The pound you lose in a hot class comes back when you drink. Fat leaves the body mostly as carbon dioxide you breathe out: about 84% of it, by the calculation of Meerman and Brown (BMJ, 2014), with the rest as water.

The afterburn keeps burning for days. After exercise your oxygen use stays raised for a while, called excess post-exercise oxygen consumption. It’s real and small. A review by LaForgia and colleagues (Journal of Sports Sciences, 2006) put it at roughly 6–15% of the energy of the workout itself. After a 300-calorie session, that’s about 20–45 extra calories, not a day of free eating.

Exercising with low appetite or nausea

GLP-1 nausea comes from food sitting longer in a slowed stomach, and it tends to cluster after each dose increase. A few adjustments help:

• Move on your better days of the week. If you feel worst in the day or two after your shot, put harder sessions later in the week.
• Choose upright, gentle options on rough days. Some people find a slow walk helps. Bending, jumping, and lying flat after a meal tend to make it worse.
• Eat something small first. A few bites of protein an hour before is enough. Training on an empty stomach when you’re already eating little can leave you lightheaded.
• Drink on a schedule. You’re getting less fluid from food, and sweating adds to the gap.

If you’re dizzy, vomiting, or can’t keep fluids down, skip the workout and message your clinician. That’s a dehydration and dosing question. GLP-1 nausea fixes covers the rest.

What to take from this

• Trial evidence: Exercise alone produces modest weight loss, a few percent at the doses most people can sustain. Combined with medication, it helped keep more weight off in the liraglutide trial.
• Guideline consensus: 150 minutes a week of moderate activity plus two strength days.
• Our position: Start with walking, water, or a bike. Add strength twice a week from the start if you’re on a GLP-1. Choose what you’ll repeat over what burns the most.

To see how activity changes your daily calorie needs, try the TDEE calculator.

What we still don’t know

The open question is whether resistance training during GLP-1 treatment preserves strength and function, not just lean mass on a scan. The large trials of semaglutide and tirzepatide didn’t randomize people to exercise, and the best-known combined trial used liraglutide. A trial that assigns GLP-1 patients to training or no training and follows grip strength, walking speed, and falls for several years would settle how much exercise is worth here. Until it exists, two strength sessions a week is a well-reasoned bet.