When you think of exercising for weight loss, what do you picture? Running? Cycling? Something that gets your heart beating hard and your body sweating heavily? Aerobic exercise has traditionally been associated with slimming down, while weight or resistance training – challenging your body to lift, push or pull its own weight, or barbells, kettlebells or dumbbells – was reserved for bodybuilders who were bulking up.
According to a survey published in 2022, around two-thirds of people in England are meeting the national exercise guidelines of 150 minutes of aerobic activity every week, but this number drops dramatically when it comes to hitting the recommended target for strength training.
But Tessa Strain, physical activity epidemiologist at the University of Cambridge, says: “Resistance training can also be a really effective way of losing weight.”
In fact, if you are hunting for a long-term exercise regime to keep you trim, a growing body of research suggests that weight training is essential. One Harvard study even found that weight training is a more successful strategy for reducing belly fat in men than either moderate or vigorous aerobic activity.
“All weight loss comes down to a calories in/calories out equation,” says Strain. At a basic level, “resistance training is a really effective way of losing weight because you’re expending energy, which involves burning calories.”
After your training session ends, your body continues to need calories for its recovery in order to repair and rebuild muscle. One 2018 study found that overall basal metabolic rate (essentially the number of calories your body burns in order to do its basic, life-sustaining jobs) can be raised for up to 48 hours after a resistance training session. Cardio workouts tend to have a less prolonged impact on your metabolism.
Nor do the benefits of resistance training end there. For long-term strength and weight management, increasing your muscle mass relative to your fat mass is key, says Strain. When you lose weight by dieting alone, you don’t only lose fat, you lose muscle too. Add weight training to the mix and you can help to preserve that muscle mass while losing the fat.
How long will it take to see results?
It depends where you look. As muscle is denser than fat, weight training will soon leave you looking trimmer and more toned. But since it weighs more, building muscle mass may not show up as overall weight change, explains Strain. This is why some super-fit athletes, such as rowers, have a BMI that would suggest obesity in other populations. So look in the mirror, not at the scales.
Can I lose weight just by lifting weights?
In theory, yes, as long as you are eating fewer calories than you are burning.
In 2021, a randomised controlled intervention trial published in the American Journal of Clinical Nutrition assigned 65 moderately obese subjects to one of three groups: diet only, diet plus aerobic training three times a week, or diet plus strength training three times a week. Those in the last group did weight resistance exercises for both the upper and lower body. After eight weeks, all three groups lost around the same amount of weight, around 9kg, but the strength-training group lost significantly less muscle than the aerobic or diet-only groups.
“What’s most likely to lead to weight loss is doing activity consistently over time, so the exercise should be the one you enjoy the most, because you’re more likely to stick to it,” says Strain. “That means resistance training offers an opportunity for people who really don’t like cardio – the ones who hate sweating it out on a treadmill.”
How many calories does weight training burn?
There is a flip side, however. “A cardio workout can burn more total calories during the session compared to a weight or resistance training workout, since the heart rate is more likely to be consistently elevated,” says Frances H. Mikuriya, the founder of Frances M Fitness.
Number crunching published in the journal Medicine & Science in Sports & Exercise suggests that a person weighing 73 kilograms will burn about 250 calories per 30 minutes of jogging at a moderate pace. If they picked up the pace, they could conceivably burn around 365 calories in the same time frame. But if they used the half hour to weight-train instead, they would be likely to burn around 130-220 calories.
How cardio and weight training work together
So cardio wins the calorie-burning competition in the short term but, Mikuriya says, resistance training is still essential “to make your body a high-rate, calorie-burning machine”. Why? Because it is a highly effective tool over the long term.
“As the body develops more muscle mass, the metabolism also increases,” she explains. And not only in the recovery period that follows a workout. “Since muscle burns more calories than fat, having a higher muscular body composition will lead to a higher basal metabolic rate. So even when at rest, the body will burn more as it requires more energy to maintain.”
When one study put participants through 24 weeks of weight training, the resting metabolism of men was raised by 9 per cent, and that of women by 4 per cent. In another, published in 2021, researchers found that one or two hours of weight training a week reduced the risk of obesity by 20 to 30 per cent, even if people did no aerobic exercise at all. Adding cardio exercise into the mix was even more protective.
Is it better to lift a heavy load for weight loss?
Not if you are starting from scratch. “If it feels challenging, it’ll be helping,” says Tessa Strain. “If you’re already quite fit, you’ll need to introduce a more intense regime to test yourself further. If not, gardening, lifting shopping and stair climbing can all contribute towards building your resting metabolic rate.”
Mikuriya agrees: “The important factor is to challenge your body, but that doesn’t need to mean heavy weights.”
Light weights and even just lifting your own body weight doing exercises like squats and push-ups will help to develop lean muscle mass and spur weight loss, she says. That said, the more strenuous the weights session, the more your body’s metabolism is elevated after training.
Mikuriya continues: “If your muscles are repeatedly subjected to the same load, they will get stronger. But over time, your strength will eventually plateau.” So what’s the key? “When that load becomes easier and you no longer reach muscular fatigue, it’s time to increase the load or the repetitions.”
How often should I do weight training for weight loss?
“The NHS physical activity guidelines say you should be doing two or more sessions of strength exercises a week that use all your major muscle groups,” says Strain.
Mikuriya recommends three to five sessions of between 30 and 60 minutes each (depending on your fitness, health and goals). “But if sessions are frequent, the recovery factor is critical as well,” she says. If you’re working your muscles hard five times a week, they won’t have had time to recover between sessions, she explains. Your next workout will be sore and less efficient. Plus, you will be tired, which can lead to injury. “Listen to your body,” she urges.
The best weight-lifting routines for weight loss
“It is vital to train properly with weights, to prevent injury,” says Mikuriya. “For novices, I would suggest learning the proper techniques first with a certified personal trainer who can monitor and correct your form.”
Weight and resistance exercises are counted in repetitions, or reps (one complete movement, like a single sit-up), and sets (a group of repetitions). A trainer will design a training programme, altering the number of reps and sets, as well as the intensity, according to your fitness and condition.
There are ways to maximise the results of your workout, however. For example, you could sit on a bench and do the requisite sets of bicep curls, but Mikuriya would be more likely to suggest you do them while squatting. Using multiple muscle groups at once requires more oxygen and thus burns more calories in the short term. Pull-ups, push-ups, squats and deadlifts are good examples of these compound exercises.
When it comes to building muscle, she would usually recommend around eight to 12 repetitions, sets of between two and six, and weights that are pushing you to around 75 to 85 per cent of the maximum you could possibly lift for one repetition.
That said, “if you are doing heavier weights one day and want to go back to the gym the following day, switch things up so you are working with lower weights and more repetitions”, Mikuriya advises. Diversification is key, she suggests, for long-term motivation, health and results.
Those who have already embraced the resistance revolution should make sure they are mixing up their repertoire, while those who have been put off by its outdated reputation should rethink – fast. Mikuriya says: “I would always suggest mixing both weight training and cardio training for the most efficient and long-term weight-loss goals.”
How to start lifting weights in later life
Month one
Lift a weight heavy enough that you can manage six to eight repetitions.
Month two
Increase the weight so that you can only lift it four to six times.
Month three
Increase the load so that you can lift for only two to four repetitions. When the last few reps feel challenging and your form is good, you will feel yourself growing stronger.
Your key movements should be push (e.g. bench press), pull (e.g. bicep curl), hinge (e.g. deadlift), squat, lunge and carry. Ask your trainer for suitable exercises and check on the correct technique. Always warm up before starting. - Tips by Eoin Ryan, personal trainer, Gymbox London, EC1N 7SS
How much exercise does it take to burn off calories?
Sugary soft drink (138 calories): 26 minutes of walking (5-7km/h) or 13 minutes of running (8km/h)
Packet of crisps (171 calories): 31-minute walk or 16-minute run
Bowl of cereal (172 calories): 31-minute walk or 16-minute run
Chicken and bacon sandwich (445 calories): 1h22 walk or 42-minute run