Research shows that on average, individuals experience a 2-4% decline in their resting metabolic rate (RMR) with each passing decade after the age of 25. What does this mean for you? It means that most people can look forward to an ever-diminishing metabolic rate, this reduction makes it harder to keep the kilos off. So what’s the point you ask? The good news is, you can change that! Let’s explore some of the things you can do to keep your metabolic rate primed and operating at its full potential to keep you healthy and lean.
How To Keep Your Metabolic Rate Primed
In part one of this articles series, I highlighted the first step to beginning the journey to becoming the best version of you. In our battle of the bulge, being happy is such a crucial key to achieving your goals. Hopefully by now you have started changing your internal language and are starting to practice the daily discipline of your ‘happy habits’ and re-training your brain to look and find the positives in your day and life and are now experienced greater levels of happiness all round.
Our Resting Metabolic Rate
As we got older, from about the age of 25 our resting metabolic rate (RMR) begins to decline. What’s that you ask? Your RMR is simply a measure by which we can determine your energy requirements to break even or the amount of energy you would need to consume at rest to neither put on weight nor lose weight, this is your energy balance. Your RMR is influenced by movement, environmental variability and food ingestion.
Understanding your energy balance requirements is crucial. Although this is still somewhat an estimation, it does give us some clarity and an indication of what your individual energy balance figure could be. All food we eat contains potential energy and this potential energy is stored in our system and has the potential to be converted into work or kinetic energy. If we ingest more energy than that which we require for our activities of daily living (ADL’s) and exceed our RMR requirements, then that energy is stored, typically as fat, this is know as energy surplus. If the energy we ingest is less than that which we require for our ADL’s, then this is know as energy deficit and we would generally lose weight.
So the body has a need for energy as we know, the expression of that energy is measured in Calories. This energy required is referred to as our metabolism. The consequences of energy imbalance lead to either weight gain or weight loss as discussed above. Our RMR adjusts itself to match our energy intake. In most cases when Calorie intake is lower than the amount to maintain normal function our RMR decreases over time. Metabolic decline occurs for three reasons: lowering of thyroid hormone output; reduced thermic effect of feeding (TEF); reduced muscle mass with inactivity or ageing.
What can I do to prevent this?
An excellent way to do that would be by getting a DEXA scan. If you’re in the Sydney CBD you can get one from Measure Up. The team up there are excellent. The report that you will get gives you really good and useful data, it measures your:
- Lean muscle mass
- Fat mass
- Bone mineral content
- And gives you an estimation of RMR expressed in calories
It’s a great way to measure fat mass and lean muscle mass changes over time and to keep you motivated and pushing on towards the best version of you.
Improve your diet
- Regular portion controlled feeding will up regulate your metabolism and help you to control your energy balance so long as you don’t exceed the total amount of energy required in that 24 hour period. Digestion, absorption and assimilation of ingested food / nutrients is an active process and it requires energy. The very act of eating increases your metabolism, the extent of this depends on which macronutrients we eat, this is known as the thermic effect of feeding (TEF).
- Increasing your protein intake will effect your energy balance directly through TEF. A healthy adult can consume between 15-25g of protein every 3 to 4 hours. Interestingly, Proteins tend to have a greater thermic effect as it requires more energy to process them.
- Achieving caloric deficit is necessary though if you have a weight loss goal but be careful to NOT push too hard! Creating a 500 k/cal daily deficit is the recommended figure 2-5 days a week only for a weight loss program that is aimed at keeping your metabolism functioning optimally. Pushing too hard or over dieting will begin to work against you! Prolonged periods of caloric deficit, generally greater than 4 to 5 days will start to have a negative effect on your metabolism. So DON’T starve yourself.
Energy expenditure through bouts of exercise is the most valuable and controllable metabolic component we have. Increasing exercise volume and intensity is the best way we can boost our metabolism. In saying that, all activity is not equal. Exercise creates an after burn effect known as EPOC or expired post exercise oxygen consumption. This also plays a part in our overall energy balance battle.
- High intensity, short duration burns a modest amount of energy during the activity, however after the activity, the total energy expenditure remains elevated for minutes to hours based on activity type and intensity. Example of this type of activity could be: Sprints, HIIT sessions, Fartlek, circuit weight training etc.
- Low intensity, long duration burns more energy during the activity, however after the activity the total energy expenditure returns quickly to the resting baseline. Example of this could be: long walk, slow constant steady state jog, bike riding at low intensity etc
Both types of aerobic exercise then are important and necessary in the battle of controlling your energy balance.
How much is enough?
Firstly, something is always better than nothing. If you’re currently not doing any type of dedicated exercise, starting with 20-30 minutes a day would be a step in the right direction. For best results, you would be disturbing metabolism daily, yes daily. A minimum of 45-60 minutes a day of moderate / high intensity exercise plus it’s also important to get your incidental or non-exercise activity thermogenesis (NEAT) done.
NEAT is the unplanned, low intensity physical activity that takes place every day including, moving around the office, caring for children and pets, fidgeting, light physical labour, walking stairs, going to the shops, mowing the lawn, stretching, preparing food etc…
The body is in constant motion, our muscles are continually being “recycled” by being regraded and re-synthesised, this is called protein turnover. Resistance training will trigger protein synthesis and have a positive effect on protein turnover by creating new muscle tissue. Muscles depend on a positive protein turnover to become bigger and stronger when stimulated by exercise. This turnover is governed by two processes, protein synthesis (new muscle being made) and protein breakdown (muscle being catabolised). Some factors that can effect this are:
- nutritional intake
- exercise habits
- health status and illness
- hormonal status
- genetic programming
Ideally what we need to be happening in life is for our rate of protein synthesis to be equal to protein breakdown or greater than protein breakdown. This would mean that there would have been a positive protein turnover and the goal of putting on some muscle would have been achieved. Basically, our main goal should be to never lose any valuable lean muscle mass so that we keep our metabolic rate primed!
As discussed earlier, age associated metabolic decline is a factor to consider, a person with an RMR of 1500 kcal at age 25 may have a RMR of 1400 kcal a decade later, fast forward another decade and their RMR may now be 1300 kcal. This metabolic decline is largely due to the losses in lean muscle mass as the years go by, with diminishing exercise and a more sedentary lifestyle it becomes harder to preserve the lean muscle tissue.
The average person will lose about 2-3 kilos of lean muscle mass every decade, because muscle is so metabolically active, the muscle loss is probably directly responsible for the metabolic decline. This suggest that metabolic decline isn’t so much aged related, rather it is largely lifestyle related.
This age related muscle loss is known or referred to as Sarcopenia. Sarcopenia is a age and lifestyle related condition that over time causes muscle atrophy / breakdown. The best form of treatment for Sarcopenia is exercise, more specifically strength / resistance training.
Resistance training then has a major role to play in keeping your metabolism primed and functioning like a formula 1 race car. In saying that,
- What kind of resistance training?
- How much resistance training?
- Where do you start?
- How do you keep it interesting?
All these questions I will address and explain in detail in the last part of this series, I will be writing about the third key, “How to effectively use resistance training to keep your muscle!”
Also, if you missed part one of this article series, “Finding your inner happiness/peace!”
I’ll leave you with some final words of wisdom,
“Give me six hours to chop down a tree and I will spend the first four sharpening the axe”
– Abraham Lincoln