If a buzzword could finish second to ‘toned’ in the weight loss industry, ‘Metabolism’ would be right up there. ‘The Fast Metabolism Diet…’ ‘The Metabolism Boosting Diet…’ ‘The Metabolism Miracle…’ ‘Jillian Michaels: Banish Fat, Boost Metabolism…’
No that last one isn’t a joke, it actually exists…
The thing is how do you know if your metabolism is slow?
What most diet gurus fail to mention in their metabolism boosting secret workouts, is that metabolism is an excruciatingly complex topic, and anyone who claims to know the ins and outs of everything metabolism is mostly full of shit.
Here is a tiny fraction of the chemical processes that add up to metabolism in the human body:
- Cellular Respiration
- Exercise (muscle contraction, movement)
- Eating (Digestion, mastication)
- Glycogen-Glucose Breakdown/Storage
- Fat-Fatty Acid Breakdown/Storage
- Protein-Amino Acid Breakdown/Storage
- Regeneration of Skin
- Regeneration of damaged cells in all of your organs (including bone, GI tract, etc…)
- Stress (which just means a stimulus placed upon the body that requires a reaction)
- Filtration via Kidneys
- Detoxification via the Liver
- Blood Circulation
And that’s just getting started…
Check out a metabolic wiki page that only scratches the surface on what some physiology textbooks discuss, and tell me your mind isn’t blown.
OK hopefully you get it by now, this is a complex topic and like most complicated subjects, a lot of people get confused when the topic comes up.
In order to understand how you can boost it, you must first clarify what it actually is, what it isn’t, and why it even matters.
Metabolism is the sum of all the reactions that take place within the body to build it up and break it down.
Pretty easy to define right? It’s a little harder to fully understand…
This includes all the things on the above list and the billions (maybe trillions) of other chemical reactions that take place in your body every day.
Where it gets confusing is that most people confuse metabolism with basal metabolism AKA resting metabolism.
Or more specifically your basal metabolic rate (BMR) AKA resting metabolic rate (RMR).
Basal metabolism is the minimum level of energy expenditure the body needs in order to maintain the vital functions within the body.
Unless you’ve had a basal metabolic assessment, which utilizes oxygen exchange to discern your RMR by breathing into a tube for a period of time, you probably don’t actually know whether your metabolism is fast or slow.
If you lived a completely sedentary life, didn’t eat and stayed at a constant temperature your BMR and your complete metabolism would be pretty darn close in terms of energy expenditure.
Basal metabolism is the biggest chunk of total metabolism in an average day at about 70-75% of your total metabolism and is really beyond your control on a day to day basis.
i.e. you’re generally not going to be able to change your basal metabolism in a day but it is also constantly in flux.
We all hear things like adding muscle to your body increases your metabolism, it does, but the mechanism is through your BMR, because lean tissues are more metabolically active than non-lean tissues like fat.
An extra kilogram of muscle is typically expected to help you burn an extra 10-13 or so extra calories at rest per day.
Now this doesn’t seem like a lot, but assuming you don’t change the amount of energy you take in, if you add it up over the course of a year, suddenly you’ve lost about 3500 calories — the amount typically quantified as a pound of fat, which is also only really a partial truth — doing nothing but being ‘your-bad-self’ with a kilogram more of lean mass.
The confusing part comes when we also hear that merely exercising increases your metabolism, and this is where some clarification is needed.
See, adding lean tissue means that your metabolism requires more energy in a day for doing nothing really outside of maintaining your vital functions, and that newly acquired muscle is now determined to be a vital bodily function.
This means your energy requirements are now larger at rest, and hence you have a ‘faster’ RMR, as the kids like to say.
Exercise on the other hand, any kind of exercise, will boost your general or overall metabolism that day by utilizing additional energy above and beyond your basic needs.
Both are good for you.
The first thing most people consider when the topic of metabolism comes up is exercise, which is an easy way to increase it, true.
However, like most things, it isn’t really that simple, now that you understand the difference between RMR and metabolism, let’s talk exercise.
Remember that adding muscle does mean boosting your metabolism, just not your RMR.
If you’re going to exercise, and I recommend that you do — in combination with some dietary changes, see below — you want to add exercise that gives you a spectrum of metabolically boosting effects.
If you lift weights, over time you’ll add some muscle, boosting your resting metabolism, and everybody can go home happy.
However you also need to consider the principle of progressive overload, so try to lift a little more each time until you can’t, then try some new lifts.
You can also change the repetition ranges you work with but for muscle gains I generally stick between 6-12 repetitions per exercise.
You can add tensile strength lifting in a 3-6 rep range too though, so don’t completely ignore higher or lower intensity training, increasing your ligament, tendon and bone strength is also ‘lean mass,’ so it is also more metabolically active than stored fat.
It also gives you a better frame for muscle building too.
Basically, if your body becomes acclimatized to lifting, it stops adapting, so mix things up every 3-6 weeks.
Think back to science class in high school, organisms adapt to stimulus only when the stimulus exceeds a certain threshold of initial tolerance.
However, energy system training shouldn’t be ignored either, just because it doesn’t have as big an output on resting metabolism, doesn’t mean it isn’t useful.
I prefer interval training over the more traditional long, slower distance exercise stuff, but I’m also a fairly busy guy.
You don’t need as much of that as you may think for heart health, but you can still do it — I ride my bike almost daily for about 20 minutes at a low intensity and I walk a lot.
Long slow endurance exercise also gets the short-end of the stick when it comes to long-term contribution because it doesn’t really contribute much to your metabolism once exercise has been completed.
It has other advantages though, it aids in recovery, contributes to heart health — making the heart bigger and stronger — and can give you a nice jolt of endorphins — if you’re resting heart rate first thing in the morning is above 60 BPM consistently, you might consider doing more of this style of exercise.
Scientists use Post-Exercise Oxygen Consumption as a method of measure for metabolic changes post-exercise or EPOC and the more intense your energy system work is the more prolonged this additional metabolic boost is — it’s about 1-36 hours depending on the research you look at and the type of exercise used, you get a longer effect for higher intensity exercise and little to no additional effect for low intensity slow distance exercise, it’s a spectrum.
Interval training is a higher intensity, so you get a little more damage, a little more necessary recovery and a little longer post-workout metabolic boost, which is why I generally favour it as ‘exercise.’
I also like it because the additional rest can keep the quality of the exercise high and the technical execution more precise.
Weight training is right up on that end of the spectrum too, hence why it generally makes sense to try an add a little muscle to your frame, even if you’re objectives are weight loss.
See my article ‘Measuring What’s Important‘ for more details on that.
Your daily activity (including exercise and other additional movements in the day) contributes anywhere from 15-30% of total daily metabolism, depending on how active you are and again is a separate issue from resting metabolism.
So I’ll give you to coles notes on all those books above, if you really want to boost your metabolism, all you have to do is just eat more and exercise more, though most of those books will tell you to eat less, even though eating boosts metabolism, as we’ll get to in a second.
Problem solved, I have answered the riddle of fitness metabolism.
Not exactly, I’m assuming that if you’re here, you probably have a weight loss ambition, and most of those books probably assume that too.
Eating more and exercising more doesn’t affect the amount of energy your body needs for it’s vital functions or it’s resting metabolism, just your total metabolism.
Eating can have a significant effect on your total metabolism, with the act of digestion contributing about 10% of your total metabolism each day.
Where things can get sticky, is that while eating increases your metabolism, it doesn’t matter how often you eat, contrary to popular opinion.
There has been a myth floating around the internetz for nearly a decade that suggests eating more frequently will boost your metabolism.
Unfortunately the theory never really held up because increasing your metabolism via food, occurs due to the thermic effect of food (TEF) and TEF remains the same no matter how frequently you eat, provided the actual type (macronutrients) and total quantity of food you consume is exactly the same that day.
Your overal macronutrient ratios are what’s important — though it’s not entirely that simple, there is variance in contribution between different types of protein, different types of fat and different types of carbohydrates; the easiest to explain is the difference between sugar and starch, obviously sugar is more easily digested even though both are carbohydrates.
If you have one large 2000 calorie meal, or 4 smaller 500 calorie meals, as long as the total food consumed is the same, the result on your metabolism is identical because your body responds to the total load per day — and actually the way your body averages it out is arguably over a few days to perhaps a week or more even.
Even though the meal frequency thing is a myth, the basics of TEF can be still be applied, you just need to do so by focusing on the quality of the food you consume, rather than the frequency.
Basically your body has to use energy to breakdown food and absorb it.
- In the case of fat your body uses roughly 3 kcal to digest about 100 kcal.
- For carbohydrates it’s a little more, about 7 kcal for every 100 kcal you ingest.
- Protein though, is through the roof, relatively speaking, it requires closer 30 kcal to digest every 100 kcal of this macronutrient.
Now most research has some variance on those numbers but just know that protein has the greatest TEF, carbs second, fat last.
The more whole the source, the bigger the boost and although eating many things raw can also increase the TEF of that food, some foods should still be cooked — like potatoes, beets, squash, poultry, many cruciferous veggies, etc…
If you want to boost your metabolism in a day a simple suggestion would be to increase your protein consumption in place of some fat and carbohydrates — *I recommend a 3-4 oz protein source with every meal for women and a 6-8 oz protein source with every meal for men, of course this depends on how frequently you eat though.
This will use up a little more energy each day, while you eat and thus ‘boost’ your metabolism, by displacing macronutrients and forcing your body to work a little harder to digest a certain type.
Eating itself also merely increases your metabolism for the day.
So Person A, who eats 6000 calories a day, has a higher total metabolism, than Person B, who eats 3000 calories a day, even if their resting metabolisms are exactly the same.
Size and Temperature
Overall size also contributes to basal metabolism, the larger you are the faster your basal metabolism typically is — outside of some very rare hormonal issues.
If you’re 260 and it’s mostly muscle, you’ll obviously have a faster metabolism than someone who is 260 and mostly fat.
However, chances are that if you’re 260 worth of fat and someone else is 220, your metabolism is actually probably faster than theirs.
Hopefully that makes you rethink a stigma surrounding the weight loss industry; That being overweight means you have a slower metabolism.
Often it actually does not, so don’t let that notion stop you from adding some metabolic boosts to your day via quality nutrition and exercise, you can still make the changes anybody else can.
However, outside of getting a Basal Assessment — and if you have the financial means I’d recommend it — there is also some loose data suggesting that body temperature can co-relate with your resting metabolic rate.
I don’t use this with my own clients but if metabolism is a concern and you’d like to know if you’re impacting it, it might be a useful rough guide.
Try tracking your temperature every morning upon walking; a good resting metabolism should typically put you around 98.2 degrees Fahrenheit or 36.8 degree Celsius at the start of the day.
However, circadian rhythm can influence this as it alters your body temperature to suit your sleep cycle, so if you’re on the low end try tracking more throughout the day to see how your temperature fluctuates.
Typically your body temperature will be at it’s peak at about 10-11 AM — depending on when you typically wake, but about 3-4 hours after waking — and 7-8 PM — again depending upon when you typically go to bed, but about 3-4 hours before you go to sleep.
Body temperature is at it’s lowest roughly 2-3 hours before we wake, so your morning temperature might be lower than you expect.
You may also see a dip in temperature after lunch from about 1-3 PM. Based on that it might be worthwhile to check every 3-4 hours for a few days and gauge where your circadian rhythm is taking you.
*Note body temperature does not always correlate with basal metabolism in research, which is why I’d recommend a Basal Metabolic Assessment as a preference (far more accurate).
I know this may come as a big surprise to people but the main factors that contribute to metabolism within our daily control are eating and exercise.
There are more specifics we know of, such as thyroid hormone and it’s involvement in the regulation of metabolism — and other mechanisms, but without medical testing it’s nearly impossible to know what specifically could be affecting you.
If your basal metabolic test seems low, relative to your body mass and body fat %, then it may be worthwhile to get some blood tests and consult your doctor.
Likewise, if you have a consistently low body temperature, this may (emphasis mine) mean you should consider a blood test and consult a doctor too.
Less than 2% of the population has any problem with their thyroid conversion and/or production, and most of that can be attributed to Iodine deficiency, and/or can be dealt with via nutrition (a clinical dietician is recommended in these circumstances).
So be realistic in your assumption of a ‘slow metabolism’ before you fall victim to the nocebo effect, essentially believing you have something you probably don’t.
Now too much eating won’t be good for weight loss — even though it increases metabolism — and too much exercise won’t be good for weight loss potentially either — too much can cause things like adrenal fatigue — so play it safe, hopefully take some of my advice and this post has gone on long enough.
Please leave a comment if you have a question.