How to Use Running to Lose Weight

The honest version first

Running is a superb way to lose weight. It’s also widely misunderstood, and the misunderstanding is why so many people start running for weight loss, step on the scale after a month, and quit.

Here is the part nobody puts on the poster: running on its own produces fairly modest weight loss. In the Midwest Exercise Trial 2, overweight and obese adults who didn’t change their diet exercised five days a week for ten months, burning either 400 or 600 calories per session under supervision. They lost about 4% and 6% of their body weight respectively.¹ That’s real and worthwhile, but it took ten months of committed training to get there.

The reason is simple arithmetic plus a bit of biology. A run burns fewer calories than most people assume, and the body partly compensates for the extra activity: some people get hungrier, some move less for the rest of the day without noticing, and total daily energy expenditure doesn’t rise as much as the exercise alone would predict.²³

So why are we still recommending it? Because the question isn’t really “how do I lose weight?” It’s “how do I lose weight, keep it off, and be healthier while I’m doing it?” And on that question, running is very hard to beat:

• Food drives the loss; activity drives the keeping off. People in the National Weight Control Registry, who have lost a significant amount of weight and kept it off for years, report very high levels of physical activity, around an hour a day on average.⁴ The American College of Sports Medicine (ACSM) position stand reaches the same conclusion: more activity is associated with less weight regain.⁵
• It changes the kind of fat you lose. Aerobic exercise reduces visceral fat, the deep abdominal fat most closely tied to diabetes and heart disease, even when the scale barely moves.⁶
• Fitness matters more than the number on the scale. A meta-analysis comparing fitness and fatness found that unfit people had roughly twice the risk of death of fit people regardless of body mass index (BMI), and that fit people with overweight or obesity had mortality risk similar to fit people of normal weight.⁷ You become healthier long before you become lighter.

Treat the plan as two levers. Food is the lever that moves your weight. Running is the lever that moves your health, and keeps the weight from coming back. Pull both and they reinforce each other.

Why running in particular

Plenty of exercise helps with weight. Running has a few advantages that matter especially for someone starting out:

• Heavier bodies burn more per mile. Running costs roughly 1 calorie per kilogram of body weight per kilometer, almost regardless of speed.⁸ A 250 lb (113kg) beginner burns about 360 calories covering 2 miles (3.2km), whether it takes 25 minutes or 35. You don’t need to be fast for it to count.
• It’s time-efficient. Running burns more energy per minute than almost anything you can sustain, which matters when you’re fitting exercise around work and family.
• It needs almost nothing. No gym, no membership, no class times. Shoes and a door.
• Progress is visible. The scale is noisy and slow. Your running isn’t: you’ll run longer stretches, recover faster and feel better within weeks, and that is what keeps people going long enough for the scale to follow.
• It changes how you see yourself. People who think of themselves as “a runner” behave differently around food, sleep and alcohol. That identity shift is hard to measure but easy to see.

Before you start: check in with a doctor

If you’ve been inactive and have known heart, metabolic (including diabetes) or kidney disease, or any symptoms like chest discomfort, unusual breathlessness or dizziness on exertion, the ACSM screening guidelines recommend medical clearance before starting.⁹ If you’re very overweight, it’s worth a visit regardless. A doctor can check your blood pressure and blood sugar, and give you a starting point to measure progress from.

Two situations need a specific conversation:

• If you take insulin or certain other diabetes medications, eating less while exercising more can push your blood sugar too low. Your dose may need adjusting.
• If you take a glucagon-like peptide-1 (GLP-1) medication for weight loss, appetite can drop so far that you under-eat, especially protein, and lose muscle along with fat. Running plus strength work helps protect against this, but agree on minimum intake targets with your prescriber.

Where to start depends on where you are

The single biggest risk for a heavier beginner isn’t the heart. It’s the legs. Running loads each leg with roughly two and a half times your body weight on every step, and while your heart and lungs adapt in weeks, bones, tendons and joints take months. A Danish study of novice runners found that those with a BMI over 30 who ran more than about 2 miles (3km) in total during their first week had a higher injury risk than those who ran less.¹⁰ That’s 2 miles across the whole week, not per run.

So pick your starting stage honestly.

Stage 1: Walk first

Start here if you can’t yet walk briskly for 30 minutes without stopping, or if your BMI is above about 35, or if you have joint pain when walking.

• Walk five days a week.
• Build from whatever you can manage now toward 30 to 45 minutes of brisk walking.
• Choose flat routes. Hills raise the effort a lot when you’re carrying extra weight.
• Stay here for at least three or four weeks, and longer if you need it. There’s no prize for leaving early.

This isn’t a waiting room. Brisk walking burns real calories, starts toughening your feet, ankles and knees, and builds the routine you’ll run in later. And every pound you lose makes the next stage easier: in one study of adults with knee osteoarthritis, each pound of weight lost removed about 4 pounds of load from the knee with every step.¹¹

Move on when 30 minutes of brisk walking feels comfortable and nothing hurts the next day.

Stage 2: Run/walk

This is the same simple plan we lay out in how to start running: three sessions a week, the same flat 2 miles (3km) each time, run as much of it as you comfortably can, walk the rest. Walk briskly for the first five minutes as a warm-up, and keep the walk breaks to one or two minutes, taken when you feel you need them.

There are three adjustments for heavier beginners:

1. Cap the running in week one. Following the Danish findings, keep the total running across all three sessions in your first week under about 2 miles (3km). In practice that means short running stretches, maybe 30 seconds to a minute, with plenty of walking. The rest of the 2-mile loop is walking, and that’s fine.
2. Grow the running gently. Add a little more running each week, not a lot. If a week feels hard, repeat it.
3. Walk on the days in between. A 20- to 30-minute walk on non-running days adds to your calorie burn without the impact, and it helps the legs recover.

Stage 3: Build the habit, then the volume

Once you can run the full 2 miles comfortably, you can start adding: a fourth session, then a slightly longer run once a week. Increase gradually, and read building weekly mileage safely before you do. Most beginner injuries come from adding too much too soon, not from running itself.

The best kinds of running for weight loss

Easy running does most of the work

Most of your running, ideally almost all of it in the first months, should be easy. That means a pace where you can talk in full sentences, which for heart rate means zones 1 and 2. No time in zone 3. If you have a heart rate monitor, see understanding heart rate zones to set them up properly.

When you’re heavier, even a slow jog may push your heart rate into zone 3. That’s your signal to walk. Walk until your breathing settles and your heart rate drops back into zone 2, then jog again. Easy isn’t about pace. It’s about effort, and early on, effort means walk breaks.

You may have heard of the “fat-burning zone”. It’s true that a higher share of the fuel you burn comes from fat at easy intensities, but for weight loss what matters is total energy over days and weeks, not which fuel you burned during the session. Easy running wins for different reasons:

• You can do more of it. Easy running lets you run three, four and five times a week. Hard running doesn’t.
• It’s kinder to your joints and tendons, which are the weak link while you’re heavier.
• It doesn’t wreck your appetite or your next session. Hard sessions often leave people ravenous and sore.
• It builds the engine. Easy running is what drives the adaptations below. More on this in why easy runs should feel easy.

Longer easy sessions, later

Once you’ve built up, one longer easy run a week (or a long run/walk) is the most calorie-dense session you’ll do, and it builds endurance. Lengthen it gradually.

Intervals can wait

High-intensity interval training (HIIT) gets a lot of attention for fat loss. A meta-analysis found that it produces similar fat loss to steady moderate exercise, in less time.¹² Similar, not better. For a heavier beginner, fast running brings higher impact forces and more injury risk, so it’s not worth it early on. Leave intervals until you’ve got several months of consistent easy running behind you.

Low-impact extras

If you want to do more than your legs can yet handle, add training that burns energy without the pounding: cycling, an elliptical, swimming or pool running, or brisk walking on a treadmill set to an incline. These let your fitness and calorie burn grow faster than your running alone safely can.

Strength training is not optional

When you eat less, you lose some muscle along with fat unless you give your body a reason to keep it. Two short strength sessions a week (squats, lunges, step-ups, calf raises, glute bridges and core work) protect your muscle, make your joints more robust for running, and help keep your metabolism up. Start with strength training for distance runners and core workouts for runners.

What your body goes through

The changes come in roughly this order, and knowing it helps, because the early weeks can feel discouraging.

Weeks 1 to 4: the hard bit. Everything feels difficult, your legs ache for a day or two after each session, and the scale may not move or may even go up. That’s normal: new training makes muscles store more glycogen (stored carbohydrate), which holds water, and muscle repair adds a little temporary fluid too. Your body is adapting, not failing.

Even in these early weeks, real things are happening. A single session of exercise improves how well your muscles take up blood sugar for a day or more afterward, and regular training improves insulin sensitivity, often before much weight has gone.

Weeks 4 to 12: the heart and muscles catch up. Your heart pumps more blood with each beat, so your resting heart rate starts to fall. Your muscles build more mitochondria (the parts of each cell that turn fuel into energy) and more capillaries to feed them, and they get better at using fat as fuel. The same 2 miles starts to feel noticeably easier, and your blood pressure often starts to come down.

Months 3 to 6 and beyond: the slow tissues. Bone, tendon and connective tissue adapt slowly, which is exactly why mileage must rise slowly. By now the running feels more natural, your waist is usually smaller, and every pound lost makes each step lighter on your knees and feet. Many people notice their sleep and mood have improved too.

The scale is the least reliable measure in all of this. Day-to-day weight swings by several pounds with water, salt and food. Weigh yourself a few mornings a week under the same conditions and watch the weekly average, and measure your waist once a month. If your waist is shrinking and your running is improving, it’s working, whatever the scale says this week.

Food and training load: getting the balance right

This is the part to be most careful with. Get it wrong one way and you won’t lose weight. Get it wrong the other way and you’ll run yourself into exhaustion, illness or injury.

Exercise is easy to undo

The calorie numbers for running are smaller than most people hope. Using the rule of thumb above, a 250 lb (113kg) runner burning about 360 calories on a 2-mile run would burn roughly 1,100 calories across three runs a week. Each of those runs is cancelled out by a single large coffee-shop muffin. In one study, people asked to estimate how much they had burned on a workout overestimated it by three to four times, and when told to eat the equivalent, ate two to three times what they had actually burned.¹³

Your watch won’t save you either. A study of seven popular wrist devices found heart rate was measured reasonably well, but energy expenditure estimates were off by between 27% and 93%.¹⁴ Treat the calorie number on your watch as a rough guess.

Set a moderate deficit

The National Institutes of Health (NIH) Body Weight Planner, built on research into how body weight actually responds to energy changes,¹⁵ is a better starting point than generic calculators: niddk.nih.gov/bwp. Then:

• Aim for a total deficit of around 500 calories a day, including your running. Weight-management guidelines recommend a deficit of 500 to 750 calories a day for most adults.¹⁶
• Don’t go below about 1,200 calories a day for women or 1,500 for men without medical supervision. Those figures are the bottom of the ranges the guidelines suggest for weight loss diets.¹⁶ Very low intakes and new training don’t mix.
• Aim to lose 1 to 2 lb (0.5 to 1kg) a week once the first couple of weeks are past. You’ll often lose more at the start, mostly water. Losing faster than that week after week usually means you’re losing muscle and setting up a rebound.
• Recalculate every 10 lb (5kg) or so. A smaller body needs less energy, so the same intake creates a smaller deficit over time. That’s one reason weight loss slows, and it’s normal.

Let food rise with training

Here is the balance that matters most: as your training load goes up, your deficit should stay the same, not grow.

When you go from walking to running three times a week, then four, then add a longer run, you’re burning more each week. If you keep eating the same amount, your deficit quietly gets bigger and bigger. For a while it feels like success because the scale moves faster. Then the warning signs arrive.

In practice:

• Consider running first thing in the morning, before you eat. For an easy run, an empty stomach is often a good idea: it’s less likely to get upset, and after an overnight fast your body burns a higher share of fat for fuel. As with the fat-burning zone, that doesn’t add up to extra fat loss on its own. A trial comparing fasted and fed morning cardio found the same fat loss either way.²¹ The real wins are a settled stomach and a run that’s done before the day gets in the way. Drink some water first and keep it easy. If you feel dizzy or shaky, or you take insulin or other diabetes medication that can cause low blood sugar, have a small snack beforehand instead.
• Later in the day, eat something before running if it’s been more than three or four hours since your last meal. Running hungry makes sessions feel harder and makes overeating later more likely. A banana, a slice of toast or a small yogurt is enough.
• Eat a proper meal after your run within a few hours, with carbohydrate and protein. There’s no need to rush.
• Eat a bit more on running days than rest days so the deficit stays roughly even across the week.
• When you add a session or lengthen your long run, add some food too. A rough guide is to add back about half of the extra calories you’d expect to burn, which keeps the deficit steady and allows for the tendency to overestimate.

Prioritize protein

Protein protects muscle while you’re in a deficit and keeps you fuller. In one trial, young men in a large calorie deficit doing hard exercise kept, and even gained, muscle on a high-protein diet while losing more fat than a lower-protein group.¹⁷ A practical target is around 0.5 to 0.7 g per pound (1.2 to 1.6 g per kg) of your goal body weight a day, spread across meals. If your goal weight is 180 lb (82kg), that’s roughly 90 to 130 g a day.

Warning signs that you’re under-fueling

Low energy availability, not eating enough for the training you’re doing, is a recognized condition in sport called relative energy deficiency in sport (REDs). It affects bone health, hormones, immunity and mood, and it isn’t limited to elite athletes.¹⁸ Watch for:

• Tiredness that doesn’t lift after a rest day, or runs getting harder week after week
• Poor sleep, irritability or low mood
• Catching every cold going
• Aches that don’t settle, especially pain in a specific spot on a bone (shin, foot, hip) that hurts when you press it or when you hop. This can be a bone stress injury. Stop running and see a doctor.
• Feeling dizzy or light-headed during or after runs
• For women, periods becoming irregular or stopping. This is a sign your body is short of energy, not a sign of fitness.

If you notice two or more of these, eat more, particularly carbohydrates, and cut back the training for a week or two. Losing weight a little more slowly is far better than an injury that stops you for three months.

Sleep is part of the plan

In a study where dieters had their sleep cut short, a far smaller share of the weight they lost came from fat (55% less) than when they slept normally, and more came from muscle.¹⁹ They were also hungrier. Short sleep makes every part of this harder. See sleep and running performance.

Other things to be careful of

• Shoes. Heavier runners don’t need special “support” shoes. Buy what feels most comfortable and cushioned on your foot, and replace them when they feel flat. More in choosing the right running shoes.
• Chafing. Thighs, underarms and under a sports bra are the common spots. Anti-chafe balm and close-fitting synthetic shorts or leggings solve most of it. Cotton makes it worse.
• Heat. Larger bodies hold more heat and cool down less easily. In hot weather, run early or late, slow down, walk more, and drink to thirst.
• Pain that changes how you run. Muscle soreness that eases as you warm up is normal. Sharp, localized pain, pain that gets worse as you run, or anything that makes you limp means stop and rest. Read common beginner running mistakes for the patterns to avoid.
• “Running will ruin your knees.” It’s a common worry, and the evidence doesn’t support it for recreational runners. A meta-analysis found hip and knee osteoarthritis rates of about 3.5% in recreational runners compared with about 10% in sedentary people.²⁰ Losing weight helps your knees further. The key is building up gradually.
• Plateaus. You’ll have weeks or even a month where nothing moves. If your waist and running are still improving, hold steady. If everything has stalled for four weeks, recalculate your intake for your new weight before you add more training.

Putting it together

1. Get checked by a doctor if you have any health conditions, symptoms or take diabetes or weight-loss medication.
2. Start where you are. Walk first if 30 minutes of brisk walking is a challenge. Then run/walk three times a week over a flat 2 miles (3km), with no more than about 2 miles of actual running in the whole first week.
3. Keep it easy. Zones 1 and 2, conversational pace, and walk whenever you drift into zone 3.
4. Add strength training twice a week and low-impact cardio on other days if you want more.
5. Eat about 500 calories a day below maintenance, never below 1,200 (women) or 1,500 (men) without medical supervision, with plenty of protein.
6. Let your food rise with your training, so the deficit stays steady rather than growing.
7. Measure the right things: weekly average weight, monthly waist measurement, and how your running feels.
8. Be patient. The first month is the hardest and shows the least. Keep going and the running gets easier, the weight comes off, and the habit that keeps it off is already built.

This article is general information, not medical advice. If you have an existing health condition, take regular medication, or have persistent pain, speak to a doctor or physical therapist before starting.

References

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