Published on 04 December 2025
From the peak metabolism of early adulthood to the hormonal changes of menopause and the muscle decline of later years, women face challenges with weight at every stage of life. Factors such as pregnancy, stress and shifting fat distribution all influence how weight is gained and managed. This article breaks down what’s happening and why, decade by decade.
Early adulthood: twenties to thirties
During this time in a woman’s life, metabolism is at its peak and is relatively stable. However, other factors such as busy careers and socialising can sometimes lead to less structured eating habits at this age. Unless you experience early menopause or become pregnant in your twenties, most women do not experience large fluctuations in their weight.
Pregnancy at any age can lead to women gaining between 10kg and 12.5kg (22lb to 28lb), putting on most of the weight after week 20. This extra weight is mainly caused by your baby growing, but it’s also a result of your body storing fat to make breast milk for when your baby is born.
It’s important to remember that maintaining a healthy weight is more challenging the older you get, so focusing on healthy habits in your twenties and thirties gives you the best foundation as you age.
Midlife: forties
Weight gain can start around your mid-forties, with most women gaining an average of 1.5 pounds a year. Often, this additional weight concentrates in around the tummy creating stubborn belly fat.
It’s important that women in their forties have compassion with themselves and their bodies as it can be hard to live a healthy lifestyle while juggling many responsibilities. From childcare to career to social-life and relationships, exercise can be a real struggle for women to incorporate into their weekly routine and self-care is often sadly neglected.
Menopause and beyond: fifties
Menopause is when your periods stop and it usually affects women aged between 45 and 55, but it can happen earlier. The sudden decline in oestrogen on the lead up to, and during, menopause can cause the following symptoms:
- Hot flushes
- Mood swings
- Slower metabolism
- Sleep struggles
- Increased stress
- Decrease in muscle mass
The link between menopause and weight gain can’t be explained by one specific reason, but the combination of a slowed metabolism, sleep disturbances and increased stress are big contributors.
Later adulthood: sixties and beyond
From the age of 30 through to 60, women lose approximately 250g of muscle each year. After the age of 70, around 15% of the total muscle is lost per decade.
Lack of proteins and calories, chronic disease such as Chronic Obstructive Pulmonary Disease (COPD) and sedentary lifestyle (especially if you’re retired) can contribute to the development of Sarcopenia. Sarcopenia is the loss of skeletal muscle mass and strength due to ageing. According to the British Dietetic Association (BDA), it is not a condition that is just about muscle loss but significantly impacts strength and activity levels. Continuing to lose muscle mass leads to mobility issues and increased risk of osteoporosis.
Women in their sixties and beyond may be retired or planning retirement. It’s important to stay active to help increase your metabolism and maintain muscle mass. Changes to metabolism are a natural part of the ageing process, but your eating habits may need to adapt to your new metabolic rate.
As well as regularly exercising to keep the additional weight off, it’s also essential to incorporate strength training to build muscle mass. Did you know that muscle tissue consumes more energy than fat tissue? So even when you’re resting, building muscle is a great way to improve your metabolism.
If you’re looking to start strength training, make sure you seek advice and support, either from a personal trainer, physiotherapist, healthcare professional, or a trusted friend to avoid injury.
Why fat distribution changes with age
Before menopause, the sex hormone, oestrogen, directs fat to the hips and thighs. However, after menopause, the decrease in oestrogen levels signals the body to store fat more around the abdomen.
This belly fat, also called visceral fat, produces hormones that increases inflammation and impacts cholesterol levels, blood pressure and is associated with increased risk of heart disease, breast and colon cancer.
It’s important to acknowledge that menopause is a stressful time, so women might experience higher levels of cortisol. Understanding the impact of cortisol during menopause is vital for managing health and wellbeing during this transitional phase.
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