Menopause and metabolism
Menopause and weight gain
Weight gain is a recurring issue when listening to most postmenopausal women, but also to those going through the peri-menopause..
As we documented in a previous post « some studies speak of an increase of 0.5 kg per year » in terms of the impact of menopause on weight gain. However, there is debate on the real role that hormonal changes linked to menopause play in the weight gain observed1. On the other hand, there is unanimity on the role of « metabolism ».
In fact, many have heard of this phenomenon. Maybe you’ve already chatted with (well-meaning) people telling you things like, « you are well aware that metabolism slows down with age, right? » , or « you should really double your daily dose of coffee, nothing like caffeine to boost your metabolism » 2.
But there are also many who have only a vague notion of what lies behind the term.
So what exactly is this « metabolism »? Does it really slow down with age? If so, how? What are the possible countermeasures?
Metabolism refers to the countless biochemical processes that allow us to exist and function normally.
It is in fact the balance (in theory perfect) between two major parts: anabolism (the synthesis of complex molecules from simpler molecules, « building up ») and catabolism (the degradation of complex molecules into simpler molecules, « breaking down »).
Anabolism is the part of metabolism in which our body is built or repaired (e.g. driving growth and mineralization of bones, or increases in muscle mass). It requires energy that ultimately comes from our food.
And that’s where catabolism comes into play: catabolic reactions break down food components (such as carbohydrates, proteins and fats) into their simpler forms, releasing energy and providing the basic building blocks needed for growth and repair.
In a “perfect” world, showcasing a « perfect » balancing act, our daily food intake would match what we need for daily anabolism.
Excess energy produced by catabolism, and not needed for anabolism, will mostly end up stored as body fat.
Basal metabolism and daily total energy expenditure
A very dangerous temptation is to avoid this fat storage by drastically « blindly » reducing food intake to limit catabolism.
The risk is to endanger our anabolic reactions: not being able to function normally or repairing our body is not a viable option. It is also counterproductive over time in terms of controlling your weight (the famous yo-yo effect).
The solution is to try first and foremost to get a good idea of what our daily total energy expenditure (TEE) is.
This is the energy we consume over 24 hours (including physical activity) while maintaining our weight..
The daily TEE is made of 3 parts3 :
- basal metabolic rate (BMR). This is the body’s minimum energy expenditure at rest. This includes the energy the body uses to keep vital functions going; for most people this represents 50-70% of the total energy expenditure.
- thermogenesis. It is the energy expenditure corresponding to the digestion of food to transform it into simpler elements and to store it; it represents about 10% of the total energy expenditure.
- energy expenditure linked to physical or intellectual activity, which varies greatly from person to person.
Once we know our TEE, we can ensure that our daily calorie intake does not exceed the calculated daily TEE.
Estimating this TEE is fairly straightforward using the Harris-Benedict equation. It calculates, quite reliably4, our BMR as a function of our height, weight, age and sex. A multiplicative factor corresponding to the activity level is then applied to obtain the TEE.
Estimating the TEE
The equation for calculating the BMR is different for men and women.
Here is the one for women:
BMR = 655 + ( 9.563 × weight in kg ) + ( 1.850 × height in cm ) – ( 4.676 × age in years )
But there are calculators online for almost immediate results..
To then obtain the TEE, you must apply an activity factor (from 1.2 if you are sedentary to 1.9 if you are extremely active).
Take the example of a 55-year-old woman, measuring 1.65 m, weighing 66 kg and practicing light physical activity, walking, twice a week (activity factor = 1.375):
her daily total energy expenditure is 1,825 kcal.
To maintain her weight, she will therefore need an intake of around 1,825 kcal per day.
« Slow » metabolism: countermeasures
BMR therefore plays a crucial role in our daily total energy expenditure.
The lower the BMR, the lower, for equal activity, the daily total energy expenditure. And therefore the more our calorie intake via food will have to be low to avoid weight gain.
The above equation clearly illustrates how the metabolism « slows down with age ». As we can see, BMR decreases by about 5 kcal per year.
In fact, our BMR drops by around 2% every ten years3.
To compensate for this drop in BMR, it is recommended, especially if you are sedentary or not very active, to play on the increase in physical activity.
In the example above, if the same woman went from light physical activity (activity factor = 1.375) to moderate activity (moderate physical activity 3 to 5 times per week, activity factor = 1.55), her TEE would increase to 2,057 kcal, or more than 230 kcal more per day.
And increasing your muscle mass allows you to increase your BMR: a lot of energy is spent on the maintenance of our muscles5.
In any case, regular and moderate physical activity (with endurance and strength training) is essential for the good health of postmenopausal women, in particular to fight against two of the greatest health risks associated with this period, osteoporosis and cardiovascular diseases.
But we should not neglect the role of thermogenesis either, even if it weighs much less than the BMR (and the daily activity) on the daily total energy expenditure. The impact is small but may be sufficient to help offset the age-related slowdown in BMR.
Thus eating more often (while keeping within the same daily amounts) is also a contributory factor to the increase in TEE, even if it remains marginal.
Moreover, ingesting 100 kcal does not have the same impact on thermogenesis depending on whether they come from lipids, carbohydrates or proteins. Digesting proteins will spend 20% to 30% of their caloric value; 5% to 10% for carbohydrates, and less than 5% for fat3.
It is not a question of doing without lipids but of respecting the recommended quantities and favoring the « good fat », extremely beneficial for postmenopausal women (including in terms of weight control by increasing lipolysis and decreasing lipogenesis).
Finally, still in the register of food, certain foods can help « boost your metabolism ».
Yes, the caffeine mentioned above is one of them6. But in the same vein, more effective and healthier, we should mention green tea6. Green tea, of which we can also recall another benefit for postmenopausal women, the contribution to the maintenance of higher levels of bone mineral density, key to fight against osteoporosis.
This overview of metabolism therefore shows that weight gain during menopause is not unavoidable. We have to admit however, that this requires a good dose of gymnastics, physical, but also intellectual!
Are you interested in the experiences of women at different stages of their menopause? Would you like a reminder of the physiology of menopause and the main symptoms? Download our free ebook, Menopause Story(ies).
1: on the other hand, there is a consensus on the fact that the distribution of fat mass changes at menopause, with an increase in intra-abdominal fat.
2: this last recommendation having been personally « offered » to the author of this article, which she listened to with some concern (or is it fear?) in light of her latest « excess coffee leading to tachycardia » experience.
3: source : Université Médicale Virtuelle Francophone (2010-2011): « La dépense énergétique ».
4: BMR can be influenced by other factors such as genetics or thyroid hormones, which the equation does not take into account. If necessary, it is advisable to prefer a medicalized approach to the estimation of BMR.
5: source : McPherron AC, Guo T, Bond ND, Gavrilova O. Increasing muscle mass to improve metabolism. Adipocyte. 2013;2(2):92-98. doi: 10.4161/adip.22500
6: source : Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 1999 Dec;70(6):1040-5. doi: 10.1093/ajcn/70.6.1040.