Metabolism refers to the hidden world of nutrient breakdown and energy release comprising thousands of chemical reactions. We can’t feel, see or touch it but it seems to have such a hold over us.
We’re told in midlife it’s slowing down, and it’s our responsibility to speed it up again! Is this yet another thing that needs our attention, that we have to whip into shape and motivate to behave?
A tough ask when we can’t measure it or stare at it.
Ah, but you can measure it I hear you cry!
True, we do have equations that assist in its estimation, but it’s incredible how these estimates become so set in stone and the number of behaviours and decisions these numbers then seem to dictate.
What is metabolism?In simple terms, metabolism is the process by which your body converts the food you eat into energy that it needs to function. This energy is used for various bodily functions such as breathing, digesting food, and physical activity. Metabolism also involves the breakdown of nutrients from food to support growth, repair, and the maintenance of body tissues. In essence, it’s the sum of all chemical reactions happening in your body to keep you alive and functioning.
How does this link to metabolic rate?Metabolism, as we just defined, is the intricate process responsible for converting the food we consume into the energy our bodies need to operate efficiently. Within this complex system, one key factor plays a vital role: our metabolic rate. Metabolic rate refers to the speed or rate at which our bodies carry out these energy-producing chemical reactions. Think of it as the pace at which your metabolism functions to transform food into energy.
What makes up my metabolic rate?It can be broken down into three parts:
- Resting Energy: This is the energy we use when we’re just sitting or lying down, not doing much. We measure this by looking at the air we breathe out.
- Eating-Related Energy: When we eat, our bodies use some energy to digest and process the food. We can measure this by checking how much energy our bodies use before and after a meal. Usually, we assume it’s about 10% of the total energy we use in a day.
- Activity Energy: This is the energy we use when we’re active, like walking, running, or playing sports. To figure this out, we subtract the resting energy and eating-related energy from the total energy we use in a day.
Myths about metabolism
There will always be someone somewhere trying to sell you a product that promises the earth. In reality though individual food components have very little significance on overall metabolic rate.
The severity and frequency of previous diets or imposed food rules will certainly impact the amount of lean muscle mass we have. However, metabolism/ metabolic rate is not a fixed entity – it is constantly open to change. Therefore, our eating and movement habits in our 40s have the potential to have positive impacts on our metabolic health. Letting go of beliefs that we cannot undo past behaviour and must therefore suffer the consequences is an important part of the equation, to free us up to take charge of our choices in midlife and feel empowered by them.
Burning fat essentially means our body is using fat as a fuel instead of carbohydrate. The body is only able to use these two fuels to generate energy. However, burning fat is not the same as using fat from our fat stores.
What tends to happen when we reduce carbohydrate intake is our fat intake proportionally goes up. This is the fuel that is then available and broken down for use as energy.
The only way to burn fat stores is to achieve a calorie deficit – which in itself is fraught with challenge. Too large a deficit will put stress on the body and create a stress response and as we spoke about above, this is a key player in how our metabolic rate works.
Higher circulating levels of stress hormones, for example cortisol alters how we use energy (i.e. our metabolic rate) and independently contributes to weight gain.
This one is complicated and again links back to stress management.
Fasting imposes stress on the body. The argument put forward by fasting advocates is that generating a level of stress is a good thing because it forces the body to adapt and become more efficient at certain things which help to protect us long-term.
The challenge with this approach though is the theory, versus the implications of implementing this within the demands of midlife. How we perceive and manage other stressors in life is key.
Fundamentally, as you’ve probably gathered by now it’s complex and there are lots of moving parts!
What I think we need to move away from is this notion that the minute we hit menopause our metabolism plummets, our bodies stop working and we need to force ourselves into diet and exercise regimes that are unsustainable and in fact, compound the problem.
Our resilience and energy reserves to address this phase of life with empowered positivity, will come from more considered, compassionate approaches. Arm yourself with the knowledge of how it all fits together and create your own roadmap to harnessing your hormones and metabolic rate through this journey.