Why is it harder for me to lose weight than it used to be?

As you get older, your resting metabolic rate declines, you move around less outside of structured exercise, and your body produces less heat after eating. These are all small shifts that happen at the same time. Together, they mean that at the same calorie intake you burn less than you used to.

The biggest culprit is muscle loss. From middle age onward you gradually lose muscle mass. In older women this amounts to an average decline in strength of 2.4% per year over ten years. Muscle tissue burns more energy than fat tissue, so fewer muscles means lower energy expenditure, even at rest. At the same time fat mass increases and your body becomes more sensitive to fluctuations in blood sugar, which makes weight management even harder.

Low levels of physical activity accelerate this process. Low physical activity is associated with a faster decline in muscle strength in older women, and that association held up in both short-term and long-term measurements. The good news: this is modifiable. Moving more slows the loss.

Losing weight at an older age is achievable, but it requires extra care. When you lose weight you lose not only fat but also muscle mass and bone density, which can be harmful in the long run. Most of the interventions that have been studied reported this additional loss. Guidance is therefore not a luxury. For the long term, beyond one year, there is hardly any research: only one small pilot study looked at sustained weight maintenance in older adults.

Strength training is the best-supported strategy for slowing muscle loss. In older adults it increases muscle mass and muscle strength and improves body composition. Three training days per week is recommended for optimal results. Note that building muscle and losing weight do not always go hand in hand on the scale. But stronger muscles do make losing weight easier in the long run.