Mysteries of Metabolism
Metabolic function is a hot topic in the fitness industry. So many things are said on the subject of metabolism, that it can be hard to know what’s true and what’s not about.
I wanted to go over 3 facts about metabolism that will hopefully give you some insight & help you on your fitness journey; be that a journey of fat-loss, gain or maintenance, general health or simply expanding your theoretical knowledge.
1. The Energy Balance Equation
Energy balance is pretty straight forward. Simply put:
- Energy (kcal) IN > energy OUT = weight gain.
- Energy iN < energy OUT = weight loss.
- Energy IN = energy OUT = wight maintenance.
So far, pretty simple. Okay, but let’s look at ‘energy out’ a little bit more in-depth. When we talk about ‘energy out’ we’re referring to Total Daily Energy Expenditure (TDEE); this is a term used to describe how much energy we expend (how many kcal are burnt) over a 24 hour period. TDEE is a combination of:
- 60-75% Resting Metabolic Rate (RMR): How much energy we expend at rest – the amount of energy required to maintain homeostasis, which is dependant on many factors including weight, height, muscle mass & physiological factors such as Thyroid function.
- 15-30% Thermic Effect Physical Activity (TEPA): How much energy is expended through physical activity – this includes both structured (e.g. resistance training) & non structured (e.g. housework) physical activity.
- Approx. 10% Thermic Effect of Feeding (TEF): How much energy is expended through the digestive & metabolic processes that take place when food is consumed.
Let’s apply this to a theoretical situation. Bill and Bob are both 6ft, both weighing in at 80kg and they both have mainly similar work & leisure activity levels resulting in the same base level of daily energy expenditure. But, Bill plays football on 3 days per week, whereas Bob prefers to get his football fix on the screen. In order for them to maintain the same weight, they will need different energy requirements – so Bob will need to eat less than Bill, as he’s not expending that extra energy through the football playing.
Now let’s take the same scenario, except we’ll say that they both play football 3 times a week, but this time, Bob has 45% muscle mass, whereas Bill only has 40%. This time around, Bill is the one who needs to eat less, as Bob’s extra muscle will be burning more energy than Bill’s for any given day.
Okay so let’s look at one more of these… This time, they’re pretty much doubles… everything is exactly the same, right down to their Thyroid function… but they still have different energy requirements. This could be because Bob fidgets excessively throughout the day whereas Bill sits as still as a Queen’s guard. Or it could be because Bob doesn’t have much of an appetite so has therefore been eating way under his caloric needs and in turn his metabolism has gone into starvation mode which has resulted in him now running on much lower energy requirements, (more on this below).
So as you can see, energy expenditure is highly dependant on the individual, which is why what works for your friend may not necessarily work for you.
2. Restrictive Diets & Metabolism
So, you might read all of that and think, “Right, all those glossy magazines are right, I need to eat as little as possible to lose weight!” But please read on before making any decisions of that nature.
It’s not uncommon for people – especially young women – to go on massively restrictive diets, sometimes even as low as 1000kcal per day.
Firstly, I would like to just say that my stance on this is that it is absolute madness. However, with everything that gets thrown at us through the media, social networking and uneducated misinformation on the internet, it’s no surprise that this appears to many as a viable option for successful and reasonable weight loss.
I’ve spoken before in my post, 21 Fat Loss Hacks (PART 1), about the dangers of eating massively calorie restrictive diets, but I want to go over that message again in this post as it’s such an important part of being healthy and is often overlooked in favour of quick-fix weight loss plans.
Oftentimes, when people do these calorie restrictive diets, they see fast results for the first week or 2, but then their weight loss plateaus, fatigue & ‘hanger’ sets in, motivation diminishes and they end up emotionally drained, often feeling like they’ve failed and then in the majority of cases, end up putting all the weight back on plus some extra, as a result of the combination of comfort eating and a decelerated metabolism.
You can probably guess where the comfort eating spurs from, but let’s talk about the decelerated metabolism.
Why would metabolism slow down if they had lost weight? Well, simply put, the body is used to receiving a certain amount of energy (calories) through food. So when we start consuming massively under this amount, it puts us in starvation mode (starvation was a real and valid threat for our ancestors, which is why we have this response built-in by default.)
What’s happening here, is that because the body thinks that we’re starving, it starts using less energy for the same amount of work – so all those necessary processes that I was referring to earlier, they still function, but the body used fewer calories to do so.
So if you want to achieve a calorie deficit in the name of weight loss, my advice would be to reduce calorie intake by as little as possible, while still achieving said deficit. The other benefit to doing it this way is that you are far more likely to actually maintain these dietary habits. Yes it might take you longer than a week to see results, but what’s more important, fast results, or permanent results?
3. Muscle Gain for Fat Loss
Another point I talked about in my post, Who Wants a Flat Tummy when it could be Defined? was the concept of gaining muscle mass to aid fat loss.
Muscle tissue contributes to approximately 10-15kcal per kg per day of TDEE, compared to fat, which contributes to roughly a mere 1/4 of this.
As I’ve said before this doesn’t equate to huge amounts, but it can however give you a little more wriggle-room when it comes to calorie consumption. At the end of the day, the more muscle mass you have in comparison to fat mass, the more calories you will burn, at rest.
Thanks for reading guys, I hope this has cleared a few things up for you 🙂
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