Why your body changes as you age

Does it feel like you’ve done nothing differently, yet your body is changing? If you are north of 40 years, then you’re likely not imagining it. I’ve just put together a bunch of information from studies that have looked at changes in body composition and health risk during the perimenopause and menopause stages. I think you’ll get the big picture that there are changes that occur which can be mitigated by lifestyle factors that are within your control.
This study found that as women headed into their menopausal transition and two years after their final menstrual period, the rate of fat gain doubled and the declines in lean mass resulted in no net change on the scales, yet quite a different body composition outcome. The changes to mass occur in both muscle and bone density (both of which are super important for optimal health as we age). This backs up other research (such as this review of studies here ) which shows that, independent of age (per se), if left unchecked, changes to body composition which impact on metabolic health are the result of hormonal changes that occur in perimenopause and into menopause. Further, there is a change in fat oxidation once past menopause (and ability to burn fat is compromised) thus we may rely more on glucose for energy if there isn’t action to intervene. This may also lead to fat gain.
The change in fat distribution (and increased fat around the middle which is a common observation among women) and a change in body weight (on average 2-3kg) occurs in the peri menopause stage, and it is thought women who gain more weight tend to experience greater vasomotor symptoms (such as hot flushes and night sweats) and in some cases experience lower quality of life. The increase in vasomotor symptoms is related to lower adinopectin, a hormone released by fat tissue that helps with insulin sensitivity and reducing inflammation. So, an interesting link there between these which is independent of the loss of oestrogen (which is also insulin sensitising) and may be another reason why the amount of carbohydrate in the diet needs to change as we age. Obesity together with a standard western diet has been found to accelerate bone mass loss in preclinical trials.
Fat oxidation rates can be changed with exercise that is of low intensity, which is one of the reasons that steady state exercise (otherwise known as zone 2 training) is seeing more airtime now. Particularly if done in a fasted state (as long as this doesn’t induce an overly stressful state, see below). An increase in fat oxidation can also be achieved through dietary manipulation. Reducing carbohydrate content relative to fat content in the diet is one way to do this (as suggested by literature in the exercise science space), and this is beneficial as we head into menopause, with the downregulation in carbohydrate metabolism that occurs when we lose the carbohydrate sensitising effects of oestrogen. Oestrogen increases glucose uptake into the muscle and can reduce liver output of glucose (glucose is what all carbohydrate is broken into when we eat it). When it declines, our ability to eat the same amount of carbohydrate in our diet also reduces. Research has shown a reduced carbohydrate diet in menopause results in lower fat gain.
Looking after sleep habits will also be important – I mean, it’s important across the board, and research has shown that women with fragmented sleep have a decrease in fat oxidation relative to having a full night’s sleep. In peri menopause we also lose progesterone’s ability to calm the brain through its impact on our GABA neurotransmitter and this is thought to be related to the disrupted sleep that can occur. Doubling down on sleep habits is essential to minimise the impact that this can have on fat gain and decreased fat oxidation.
Reducing stress is another important lifestyle factor which is challenging when there is family, children, a career, and a household to manage, not to mention anything extracurricular outside of that. In women who aren’t necessarily overweight there is an increase in adipose tissue in the abdominal region (i.e. belly fat) with excess cortisol levels. Stress is stress to the body, and be it emotional, psychological, physical stress, if steps aren’t taken to manage it, then excess belly fat can be a consequence. A mindfulness intervention that focused on changing eating behaviour (and stress eating) was found to be beneficial for cortisol response and reducing belly fat.
Strength training reduces vasomotor symptoms, increases insulin sensitivity, changes body composition and has a favourable impact on adinopectin levels. There is so much good that can come from strength training. I really wish more women could be convinced to do it. I would say around half of those I speak to say they know they “should” but don’t do it anyway. Unfortunately house cleaning, gardening and even pilates doesn’t take the place of building strength via a strength training routine. I’m not suggesting that other activities aren’t valuable, they just aren’t providing the same stimulus. Strength training is also so important for bone density.

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