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weight training is one way to improve metabolism over 40 - woman prepares to deadlift a barbell

Metabolism Over 40 – What Works For Athletic Women


Metabolism over 40 – and how to boost it – is a very popular topic that brings up countless internet searches and social media posts.

However, it’s time to move beyond general advice of “eat less, move more” or useless products like metabolism boosting pills. You deserve a more educated discussion of the topic.

Many athletic women begin to notice body composition shifts or changes in performance once peri-menopause begins.

And as a result, it’s common to start eating even less and exercising even more to combat these changes.

However, in an effort to boost metabolism and lose weight, athletic women over 40 often end up with poorer performance, less energy, muscle loss, and lower strength. Why?

This is the final installment in a four-part series on energy and metabolism over 40.

understanding metabolism over 40 for athletic women - woman walks into a gym holding lifting shoes

Why Eat Less Move More Doesn’t Work for Athletic Women and Metabolism Over 40

Some lower calorie diets may be appropriate for sedentary people.

However, they’re not for active women over 40 who are doing strength training programs, HIIT, and / or lots of endurance training.

Consistent training requires fueling.

Your diet affects energy balance, and energy balance affects diet.(1)

The strength and conditioning adaptations you want require adequate nutritional building blocks daily. 

Athletic women over 40 who care about performance need to think carefully about attempting weight loss. It sounds counterintuitive, but you don’t just want to “lose weight.”

It’s common to attempt weight loss by slashing food intake and pushing yourself to train harder.

If you push protein too low and skimp on strength training, the weight you lose will be muscle and fat, not just fat like you might think.

You do not want to lose muscle.

Here’s an example of how this can play out.

Low energy flux might look like:

Eat 1000kcal

Use 1500kcal

This results in low energy availability which has negative effects on metabolism, hormones, and performance.

High energy flux:

Eat 2000kcal

Use 2500kcal

Both scenarios result in a 500kcal deficit.

However, the effect on metabolism is likely to be different.

lifting weights is one way to boost metabolism over 40 - getting ready to strength train

Changes to Metabolism Over 40

Metabolism includes several moving parts.

Yes, reproductive hormones and menopause status can play a role. This is harder to control.

What is more in your control? Lifestyle factors such as exercise, nutrition, sleep and stress management.

Let’s focus in on muscle.

Once you’re over 30, you’re already experiencing age-related muscle loss unless you take steps to reverse it.

On top of age, women in peri-menopause and post-menopause lose muscle faster because of the fluctuations and eventual loss of estrogen.

Estrogen – specifically estradiol (E2) – is very important because:

  • It has an anabolic – building – effect, especially on muscle.
  • It’s important for maintaining muscle satellite cell function.(2)
  • It helps promote insulin sensitivity.

Some of these play a role in changes to muscle mass status and metabolism throughout the menopause transition and beyond.

And it’s why low calorie diets, low protein diets and a lack of weight training (or lifting too light all the time) have particularly poor results for women over 40.

Muscle is lost, metabolism adapts downward, and body composition changes.

Women – especially those who love training – often continue the vicious cycle of trying to eat less and move more.

What is Metabolic Adaptation?

Exactly why does eating a lot less cause metabolic adaptation?

Lower energy flux – as described above – would have negative consequences on metabolic adaptation over time:

  • Decreased resting energy expenditure
  • Decreased non-exercise activity

With a low energy flux, your body also becomes more efficient at absorbing energy from the food you eat.(3)

Any loss of muscle tissue has an impact on your resting metabolic rate and thus overall energy expenditure:

  1. As your body tries to counter a sustained low energy flux, resting metabolic rate drops.
  2. Your non-exercise activity falls as your body attempts to conserve energy.
  3. Your body compensates by lowering your total energy expenditure relative to your energy intake. 

Even if you try to maintain energy expenditure through exercise, this isn’t the best plan. It’s now likely to be more efficient.

This means you burn less energy than you originally did for the same intensity and duration of exercise.

And with all the compensations, the gap between what you take in and what you’re using shrinks. As a result, you hit the dreaded weight loss plateau.  

weight training is one way to improve metabolism over 40 - woman prepares to deadlift a barbell

Can you minimize these compensations while trying to nourish your body, maintain energy levels, train hard, and support a healthy body composition? Yes. 

Research in this area suggests that maintaining a high energy flux could be a key factor in successful body composition management.

Higher energy flux is useful because:

1) You expend more energy by maintaining a higher muscle mass.

  • This helps maintain a higher resting metabolic rate, the most significant aspect of your total energy expenditure. It also results in a higher thermic effect of food (especially when protein intake increases).
  • When there is more muscle mass, those extra pounds helps increase the energy spent through physical activity.

2) You’ll expend more energy in physical activity (especially through non-exercise physical activity).

  • Simply put, as you move through the world with more muscle, you use more energy to do so.
  • You give yourself more food to cover your energy and nutrient needs.

3) You’ll have better appetite control. 

  • Both food and physical activity can regulate appetite hormones and food preferences. Lack of sleep also affects appetite regulation. Hunger signaling is much lower when you’re in higher energy flux (3).
  • The desire to over-eat energy dense food goes down. This can include thinking about food constantly, watching cooking shows, saving recipes, etc.
  • Total energy intake modified when we more closely match our energy intake to our energy expenditure. Remember from above, our training and nutrition are dependent variables.

4) You can eat more and improve satiety.

  • This is especially true for women who get caught in the loop of tightly restraining their diet followed by periods of binge eating.
  • Focusing on meals with mostly whole foods is key. By including high-quality protein foods and higher fiber carbs, you can actually eat a very fulfilling meal. You’re not ravenous as you approach meal time, and you finish the meal with a high-degree of sustained satiety after.
  • Being able to eat more helps in social situations too.(1)

What Does Research Say About Energy Flux?

The main focus of this article has been to introduce energy flux and associated concepts, rather than doing a deep dive into the literature on the topic.

However, there’s one piece of research I want to highlight, and it’s probably my favorite in this space.(4)

Like all research, this particular study is not without its limitations. We should always think critically. 

However, it has a very good and thorough design with a 2-3 year follow up period. All the subjects were women which is still not very common. Specifically, the study focused on over 200 adolescent and college-aged women.

Low energy intake plus low energy expenditure (low energy flux), not energy surfeit, predicts future body fat gain” is the study’s title.

I highly recommend it for anyone interested in reading more on this topic. [Note: “Surfeit” means a surplus.] 

Conventional wisdom says that an energy surplus drives fat gain. This then pushes women toward creating a large daily energy deficit – dieting – to lose fat.

deadlifting a barbell - strength training helps build muscle

The hypothesis tested was that body composition (in terms of future body fat gain) was better managed when energy intake more closely matched energy expenditure. In other words, what happened to body fat when subjects ate and moved more? 

The study conclusion is that a low energy flux predicted future increases in body fat. On the other hand, a high energy flux appeared to prevent fat gain. 

The results suggest that consuming a high amount of energy – by eating more and exercising – can help prevent weight gain. This is in contrast to a typical dieting strategy which involves restricting energy intake for a long period of time.

The protection of a high resting metabolic rate (RMR) is key. 

RMR is protected by both the higher energy intake, as well as the ability to maintain high levels of energy expenditure. 

“Because RMR is the largest constituent of daily total energy expenditure and some (but not all) studies show that low RMR predicts future weight gain, high physical activity coupled with high energy intake may protect against weight gain.”

The authors noted something else: energy conservation. 

Low energy intakes, over time, lead to a reduction in intentional physical activity levels. That can show up as missing workout sessions, cutting sessions short, and being unable to maintain high intensity.

And reductions in non-exercise activities, where you’re less likely to walk anywhere, default to taking the car even on short trips, put off chores around the house, etc.

As I mentioned above, this study isn’t without its limitations.

  • There are valid questions around being able to accurately assess diet over the relatively long duration of this study.
  • Are there distinct macronutrient effects between the low- and high-energy flux groups? In other words, did the high energy flux groups eat a distinctly different diet to those with a low energy flux? 

Despite some limitations, the concept of energy flux provides a helpful framework for athletic women over 40.

Instead of chronically eating less, let’s look at how to apply this in the real world.

How to Increase Your Metabolism Over 40

While the theory of energy flux seems sound, where the rubber hits the road is always in the real world application. 

This might be challenging if you believe that massive calorie restriction is the only way.

Learning your way out of this deep seated programming takes practice. But with time and consistency, you can escape the endless cycle of diets.

The good news is that you can speed up your metabolism over 40 in meaningful ways.

The three methods below are more impactful than drinking green tea or taking cayenne pepper pills for the supposed “metabolism boost.”

1) Start with eating more energy, specifically protein intake to improve metabolism over 40. 

  • Most women I work with are not eating enough protein to support their health and performance goals. Increasing protein intake helps regulate appetite and satiety levels. This is especially important in preventing hunger and overeating non-protein energy foods (read as: snacking and bingeing). 
  • Protein has the highest TEF – thermic effect of food – increasing energy expenditure to digest food and absorb nutrients. 
  • Protein helps to build and protect lean body mass. This directly impacts your resting metabolic rate (RMR), the largest component of your daily energy expenditure.

2) Add strength training to build lean mass (5) (supported by the additional protein energy intake mentioned above). 

  • Here I’m talking about building muscle, bone, stronger tendons, ligaments, and all other connective tissues associated with moving your body under load. 
  • Each strength workout in and of itself doesn’t “burn a lot of energy” (by comparison to more aerobic-based exercise). However, you’re playing the longer, more infinite game of building more metabolically active tissues to help increase RMR.
  • Once you’re in your 30s, you begin to lose muscle. This plays a role in metabolism slowing over time. Muscle loss happens more slowly at first but accelerates once you’re in your 60s.

You’re also more likely to see improvements in energy used during your main exercise sessions. This is due to:

  • more consistency (fewer missed sessions)
  • maintaining higher intensities in weight training and cardio conditioning
  • making progression over time and improving fitness levels

3) Look for opportunities and strategies to build more non-exercise activity into your day

  • Simply put, move around more often. NEAT increases the number of calories used compared to dedicated cardio and conditioning sessions. 
  • Tracking your daily step count can be one way of monitoring NEAT. You could track your current baseline then set goals and strategies to increase it. 
  • My preferred method, however, is to track time spent walking each day (avoiding the temptation to ‘cheat’ the step counter). Look for opportunities to add short walks, even in 5-minute blocks, throughout the day, up to a reasonable daily total.
  • Add movement snacks to your day.

These three anchor strategies combine to drive energy usage up. 

I generally don’t recommend you start by adding long cardio sessions, which is what women often do when thinking they need to increase energy output. 

Many women will struggle to find the time (and energy) for this. In some instances, you might need to do fewer long duration cardio sessions to make room for strength training. 

athletic women over 40 need proper nutrition, lifting and increased non exercise activity to keep metabolism strong over 40 - photo of a woman sitting on gym floor smiling

Summary of Metabolism Over 40

Energy balance and metabolism are key concepts that athletic women over 40 must understand. We covered this in the entire four-part series. (See part 1, part 2, part 3)

A summary of this article on metabolism over 40:

  • Age related muscle loss – sarcopenia – starts in your 30s unless you take steps to counteract it. Hormonal changes during peri/post-menopause speed this muscle loss, alter insulin sensitivity, and more. Loss of muscle negatively impacts energy expenditure.
  • Many athletic women try to eat less and move more to address changes in body composition like fat gain. This results in low energy flux and negative adaptations to metabolism.
  • Eating more – especially enough protein – allows you to spend more energy through movement, exercise, and digesting food. It also helps you build more muscle. All of these help you boost metabolism over 40.

Fine tune your fitness and nutrition plan with a knowledgeable professional who can help you with:

Are you an athletic woman over 40 who wants a customized plan? Apply to work with me!


1 Manore MM, Larson-Meyer DE, Lindsay AR, Hongu N, Houtkooper L. Dynamic Energy Balance: An Integrated Framework for Discussing Diet and Physical Activity in Obesity Prevention-Is it More than Eating Less and Exercising More? Nutrients. 2017 Aug 19;9(8):905. doi: 10.3390/nu9080905. PMID: 28825615; PMCID: PMC5579698.

2 Collins BC, Arpke RW, Larson AA, Baumann CW, Xie N, Cabelka CA, Nash NL, Juppi HK, Laakkonen EK, Sipilä S, Kovanen V, Spangenburg EE, Kyba M, Lowe DA. Estrogen Regulates the Satellite Cell Compartment in Females. Cell Rep. 2019 Jul 9;28(2):368-381.e6. doi: 10.1016/j.celrep.2019.06.025. PMID: 31291574; PMCID: PMC6655560.

3 Melby CL, Paris HL, Sayer RD, Bell C, Hill JO. Increasing Energy Flux to Maintain Diet-Induced Weight Loss. Nutrients. 2019; 11(10):2533. https://doi.org/10.3390/nu11102533

4 Hume DJ, Yokum S, Stice E. Low energy intake plus low energy expenditure (low energy flux), not energy surfeit, predicts future body fat gain. Am J Clin Nutr. 2016 Jun;103(6):1389-96. doi: 10.3945/ajcn.115.127753. Epub 2016 May 11. PMID: 27169833; PMCID: PMC4880998.

5 Aristizabal JC, Freidenreich DJ, Volk BM, Kupchak BR, Saenz C, Maresh CM, Kraemer WJ, Volek JS. Effect of resistance training on resting metabolic rate and its estimation by a dual-energy X-ray absorptiometry metabolic map. Eur J Clin Nutr. 2015 Jul;69(7):831-6. doi: 10.1038/ejcn.2014.216. Epub 2014 Oct 8. PMID: 25293431.

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2 Responses

  1. I stumbled on this page while googling metabolism for athletes approaching middle aged. Thanks for this well-informed 4-part series! This was well researched and I appreciate that you cited your sources (a lost art form in the fitness world). This really resonates with me and validates the confusing experiences and advice I’ve been getting from (mostly male) trainers as I enter my mid-30s. I’ve been a competitive athlete my whole life which kept me lean, but pandemic and job change meant that in spite of keeping my workouts consistent and eventually increasing them because I’ve taken up triathlon, I’ve been gaining weight to the point where I have substantial midsection weight. It is crazy to me because in a lot of ways I’m in the best athletic shape of my life but all anyone sees is I’ve gotten “fat”. CICO is basically the only model I’ve been suggested to lose the weight, but endurance sports need fuel!! It’s a calorie death spiral with no alternative. I appreciate how you made the science easy to follow and the metabolic adaptation and will try to include what I can in daily movement to my lifestyle to see if it helps.

Steph Gaudreau

Hi, I'm Steph Gaudreau (CISSN, NASM-CPT)!

Nutrition and fitness coach for women, Lord of the Rings nerd, and depending on who you ask, crazy cat lady. My mission is to help you fuel for more: bigger muscles, strength, energy, and possibilities. We’ll do it with my signature blend of science, strategy…and a little bit of sass.


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