You cut back on food and add more walks or runs, and the scale moves. What it does not show is what else is coming off with the fat, and that part decides how strong you are years from now.
A trial in the New England Journal of Medicine took 160 adults aged 65 and over with obesity. For six months, three groups dieted: one added cardio, one added strength training and one did both. A fourth group made no changes. 141 people finished the study.1
Fat came off in every diet group, and by about the same amount: 6.3 kg with cardio, 7.3 kg with strength training and 7.0 kg with both. The difference was in what else came off. The cardio group lost 2.7 kg of lean mass, which is the muscle and everything else in the body that is not fat. The strength training group lost 1.0 kg, and the group that did both lost 1.7 kg.1
Bone went the same way. Hip bone density fell 2.6% in the cardio group and 1.1% in the group that did both, and did not change in the strength training group.1 All three exercise groups did better than the group that made no changes on a test of everyday physical tasks, and the group that did both improved the most.1
These were older adults, and the study ran for six months. The pattern is the useful part: the same fat came off either way, and the group that strength trained kept more of the rest.
The LIFTMOR trial in Australia took 101 women past menopause, aged around 65, whose bone density was already low. Half did supervised heavy lifting and jumping for 30 minutes twice a week for eight months. The other half were the comparison group.2
The women who lifted gained 2.9% in bone density at the spine and 0.3% at the hip. The women who did not lift lost 1.2% at the spine and 1.9% at the hip over the same months.2 Bone density was measured on a scan, and the study did not run long enough to count fractures.
A review of strength training research by Wayne Westcott puts the gain in bone density from strength training at 1% to 3% across studies.4
Your body burns calories all day just keeping you alive, and each tissue burns at its own rate. A study of 131 healthy adults measured the energy each organ and tissue uses at rest. Muscle came out at about 13 calories per kilogram a day, and fat at about 4.5.3 So a kilo of muscle burns about three times what a kilo of fat does, even while you sleep.
One kilo of muscle on its own is a small number of calories, so the bigger point is keeping the muscle you have. In his review, Westcott reports that ten weeks of strength training added about 1.4 kg of lean weight, took off about 1.8 kg of fat and raised resting metabolism by about 7%.4 The same review says inactive adults lose 3% to 8% of their muscle every decade.4
The standard recommended amount of protein, 0.8 g per kilogram of body weight a day, is set to keep you healthy. It was not set for building muscle. A 2016 review led by Stuart Phillips at McMaster University suggests that at least 1.2 to 1.6 g per kilogram a day is a better target for healthy ageing.5 An international expert group, PROT-AGE, recommends at least 1.0 to 1.2 g for people over 65, and 1.2 g or more for those who exercise.6
To build muscle, the strongest evidence comes from pooled trials of people who strength train. A review of 49 trials and 1,863 adults found extra protein added strength and lean mass, and the gains levelled off at a best estimate of about 1.6 g per kilogram a day. Because that estimate could sit as high as 2.2 g, the authors suggest up to 2.2 g for people who want to build the most.7 A 2022 review of 74 trials found the same direction: more protein during strength training gave small extra gains in lean mass and leg strength.8
The gains are steady rather than dramatic, and they come with the training. Every trial in the 49-trial review had people strength training. The same review found extra protein added a little less muscle the older people were, which is one more reason not to sit at the minimum.7
Eating less and doing cardio takes fat off, but in the trials it took more muscle and bone with it. Strength training took the same fat off and kept more of the rest, and with enough protein it gives your muscle something to build with. That muscle burns more at rest and keeps you strong. Eighty Thirty works out your daily protein and keeps count for you, so you eat better and stay strong for the things you love. Start with our free macro calculator.
In a six-month trial of 160 dieters aged 65 and over, the cardio group lost 2.7 kg of lean mass and the strength training group 1.0 kg, while both lost about the same fat.1 The difference was whether they strength trained while they ate less.
It can. In the LIFTMOR trial, women past menopause with low bone mass did heavy lifting and jumping twice a week for eight months and gained 2.9% in spine bone density. The women who did not train lost 1.2% over the same months.2
To keep your muscle as you age, researchers suggest at least 1.2 to 1.6 g of protein per kilogram a day.5 To build more alongside strength training, a review of 49 trials put the best estimate at about 1.6 g, with up to 2.2 g suggested.7
A little. A kilo of muscle burns about 13 calories a day at rest, against about 4.5 for a kilo of fat.3 In Westcott's review, ten weeks of strength training raised resting metabolism by about 7% and added about 1.4 kg of lean weight.4
Both took fat off in the trial, by about the same amount.1 The group that strength trained lost far less lean mass and kept its hip bone density, and the group that did both improved most on everyday physical tasks. Strength training is the part that keeps your muscle.1
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