Metabolism In Your 40s – How To Maintain A Healthy Weight

Has your body weight crept up in recent years? It’s not uncommon to experience changes to your metabolism in your 40s – but the reasons why might surprise you. Let’s explore what you need to know to maintain a healthy weight throughout your 40s and beyond.

The biggest myth about metabolism in your 40s

When I speak to women about their health, they often mention gaining weight once they hit their 40s or even late 30s. And it’s often followed up with ‘but that’s normal, because your metabolism slows down/everyone gains weight in their 40s/weight gain is inevitable during perimenopause’.

But it’s time to bust this idea!

Yes, your metabolism may drop with age. But it’s probably not as much as you think, and much later than you assume!

In fact, the latest research found that the adult metabolic rate (post-puberty) doesn’t really change until you hit your 60s. And even once you reach your 60s? The study found the metabolic drop was only by 0.7% per year.

Maybe this myth even feeds into the problem. When you believe it’s inevitable that you’ll put on weight, you don’t take action when it happens because you don’t think you can stop it!

What influences metabolism in your 40s?

So why does weight gain occur in your 40s if it’s not just part of getting older? There is a lot going on for most of us during this stage of life. You may be juggling unruly teens, elderly parents, career peaks, relationship challenges… the list goes on. All of this adds up to an increase in lifestyle factors. Your baseline stress level is probably the highest it’s been, exercise may be intermittent or out the window, and convenient food choices sneak in more frequently.

But that’s not the only thing going on. A big part of the metabolic shift is thanks to perimenopause. During this transition period, a lot of factors can get thrown off if your body is out of balance. There are 3 core causes of a slower metabolism & increased weight gain during this time.

Thyroid function

Another common concern during your 40s is reduced thyroid function. People are more likely to develop Hashimoto’s (an autoimmune thyroid condition) between 30-50 years old, and it’s more common in women.

The hormonal changes of perimenopause may be to blame. Low progesterone can affect thyroid hormone production and trigger autoimmunity. Fluctuating oestrogen can also play a role by increasing the compound that binds to thyroid hormone in the blood.

The thyroid is responsible for your metabolic rate. So if your thyroid function reduces, your metabolism will slow as a result.

Insulin resistance

There are a lot of hormones that can be thrown off during perimenopause, including insulin. Unfortunately, perimenopause is a perfect storm for insulin resistance to develop. And once your cells are resistant to insulin, you store more fat and gain weight easily – even if you’re eating a normal amount.

The other big concern? Insulin resistance becomes a vicious cycle if you don’t act. It causes you to crave more carbohydrates and sugar, which feeds into the insulin resistance picture. This also plays a role in exacerbating the other factors impacting on your weight.


You’ve likely heard this from me a million times before, but inflammation and inflammaging always need to be considered! Inflammation feeds into insulin resistance, thyroid function, hormone imbalances, and of course premature ageing.

Studies are starting to link inflammation with weight gain. Of course, excess body fat can cause inflammation, but there is evidence to suggest this is a two way street. So chronic low-grade inflammation could be contributing to your weight gain.

So how can I stay a healthy weight?

The answer is simple. Whether you want to lose weight or prevent future weight gain, the key is addressing the underlying issues!

That means tackling any insulin resistance, balancing hormones, reducing inflammation and supporting thyroid function. But these be difficult to identify if you’re not sure what to look for, so the best option is to work with a qualified practitioner.

If you’re struggling with your metabolism in your 40s, know that weight gain doesn’t have to be inevitable!

Let’s jump on a FREE Pre-Screening Call to talk about how we can get you looking AND feeling amazing.

Susie Garden | Clinical Nutritionist & Naturopath

Are you a woman feeling stressed, flat and experiencing the challenges of peri/menopause?
It’s time to reclaim your youthful energy, radiance and self-assurance (and your ideal weight).
I’m here to help with my proven method.

Book your complimentary Pre-Screening Call here, and let’s see how I might help you.