Today we are talking about metabolism! Is it the reason you can’t lose weight? Has it withered away to nothing as you have become older? 

Well, I am here to tell you for a vast majority, like 99% of you, none of the above applies. Your metabolism is very much still present and intact. It might be a little bit reduced due to your weight-loss/dieting history, but your metabolism never disappears or becomes non-existent. 

In some medical conditions like hypothyroidism, there can be up to a ~25% reduction in metabolic rate if left UNTREATED, but once it is treated this concern is no longer relevant. Yes, there are other conditions, but they are exceedingly rare, and again for 99% of you these don’t apply. 

Ok great. So why am I not losing weight? 

The reason you are unable to lose weight is simply that you are not in a calorie deficit. This principle still holds true across the board regardless of medical condition, medications, or hormones. 

Calories In < Calories Out = Weight-loss

Kapeesh?! The ‘Calories In’ portion of this equation is obviously the food you eat, but the ‘Calories Out’ aspect has multiple components. 

The main component of Calories Out is your metabolism or metabolic rate – in fact, it makes up ~70% of the Calories Out for most individuals. So you can probably see why ‘fitness experts’ and now ex-physicians turned nutrition specialists tend to focus so much attention on increasing your metabolism! 

The rest of the Calories Out equation is composed of both your exercise and non-exercise activity; there is also a small number of calories required to digest the food you eat.  

Go on… 

Now for a bit of science speak. When people are talking about metabolism, they are often referring to what people much smarter than I call your Basal Metabolic Rate (BMR) or your Resting Metabolic Rate (RMR). For the physiology nerds out there – yes BMR and RMR are slightly different, but for our purposes, they are the same. 

Your BMR is the amount of energy that your body requires to keep the proverbial ‘lights on.’ It is the energy your body uses by simply existing, digesting food, pumping your blood, etc. Basically all the background stuff that allows you to be the wonderful human being or troll in my comments section that you are without you even realizing it! 

Your BMR changes as you gain or lose weight – because you are physically larger or smaller, therefore, require more or less energy to keep the ‘lights on.’ Similarly, adding muscle mass via resistance training can lead to an increase in BMR as muscle is more metabolically active than other tissues. 

Further, your metabolic rate can also change based on your calorie intake. We call all of this Metabolic Adaptation. People often talk about this concept in terms of weight-loss and being in a calorie deficit, BUT metabolic adaptation can also occur when you are in a calorie surplus. 

This all ties back to the idea of Set Point Theory – which is the idea that our bodies have a specific weight they like to stay at therefore if you are in a calorie deficit and losing weight your body will metabolically adapt (reduce BMR, reduce fidgeting, become more fuel efficient, increase your hunger/cravings, etc.) in order to make you gain the weight back to the level you were prior. 

Similarly, when you eat in a calorie surplus, your body will metabolically adapt the other way (increasing BMR, reducing hunger/cravings, becoming less fuel efficient, etc.) all in an effort to prevent or limit the amount of weight you gain when eating in a calorie surplus. These efforts are all done to try and maintain your body at its current weight or current Set Point.  

Obviously, there are genetic and environmental differences in this regard. Some people adapt more easily than others, and some people have larger adaptations. In general, all of us have some degree of adaptation that occurs as these systems were built to keep us alive. Of course, 30,000 years ago weight-loss meant food was scarce; we weren’t sitting around in our caves trying to get skinny for our cousin’s wedding.   

Ok, so calorie deficit = lose weight, right? 

An area where I see many people go wrong in terms of their weight-loss journey is restricting their calorie intake to below their BMR. To give you an analogy you can think of your BMR as your monthly budget. Not the extra stuff like tickets to the Lady Gaga concert or that Air Fryer you want to buy. 

These would be your expenses that are absolutely necessary for you to exist month to month. Things like your food, housing, gas, electricity, maybe some clothes, perhaps your vehicle, or at least bus fare to get to work and so on. 

I am sure some of you might say you can’t exist without your air fryer or seeing Lady Gaga in concert. While I would beg to differ, I have no leg to stand on as I don’t think I could exist in Canada without underground parking. 

Anyways, at the end of each month, you want to have made at least enough money to meet your basic needs/necessities; but what happens if you don’t make enough money to meet those needs? Well, you either go without or you go into debt to make ends meet. 

A similar type of situation happens with your body. If your calorie intake is below your BMR you are not providing your body with enough energy to meet its basic metabolic needs. So what will your body do? 

Yes, it will tap into your fat stores or savings; however, it will also metabolically adapt – which will lead to an increase in hunger, cravings, and food-seeking behaviors. It will get you to move less and more rapidly strip away your muscle tissue. All of which will slow your metabolic rate and increase your chances of binging and overeating. Eventually leading to whatever diet you are currently on no longer being bearable, you reverting back to your old patterns, and your weight then increasing to where it was or possibly higher. 

Karen, I am not saying the above does not happen when you are in a smaller calorie deficit above your BMR. Of course it does. However,  it is much more manageable because your body is receiving enough calories to keep the ‘lights on.’ 

Your basic metabolic needs are being met so hunger/cravings will be lessened, you will retain more muscle mass (especially if you are eating more protein and engaging in resistance training), and your metabolic adaptation will be reduced to a lesser degree. Best of all you will probably feel better and be less of an asshat to those around you. 

So is there a downside?

Well, you will lose weight more slowly. Or will you? 

You see, you might lose weight more slowly during this weight loss attempt but if we look at sustainability and long-term weight loss vs. yo-yo dieting, the above approach will take less time in the long run. 

Just like your monthly budget – if you try to find ways to reduce your spending more sustainably (i.e. downsize your apartment or get a roommate) vs. living like a monk for bursts of time to save large chunks of money quickly and then rebound by splurging because you hate living like a monk and want to be presentable at the Lady Gaga concert. At the end of the year, you will have more money and probably be happier.     

There are a million BMR calculators you can find via Dr. Google. I like this one here. Different calculators will give you different numbers, but they will all be in the same general ballpark. Or if you have access to it, you can get your personal RMR measured! 

Then when creating a calorie deficit for yourself don’t go below this number. You will still lose weight and be a hell of a lot healthier for it. Of course, you can adjust as you progress – when you become smaller your BMR will go down, or if you increase activity, you might need even more calories. This is where trial and error comes to find what best works for you and your lifestyle! 

I think that is enough for now. Until next time my friends, always remember that small tweaks lead to massive peaks. 

– Dr. Dan 

References: 

• Norton L, Baxter H. The Complete Reverse Dieting Guide. 2019.

• Weiss EC, Galuska DA, Kettel Khan L, Gillespie C, Serdula MK. Weight regain in U.S. adults who experienced substantial weight loss, 1999-2002. Am J Prev Med. 2007 Jul;33(1):34–40.

• Lark DS, Kwan JR, McClatchey PM, James MN, James FD, Lighton JRB, et al. Reduced Nonexercise Activity Attenuates Negative Energy Balance in Mice Engaged in Voluntary Exercise. Diabetes. 2018 May;67(5):831–40.

• Trexler ET, Smith-Ryan AE, Norton LE. Metabolic adaptation to weight loss: implications for the athlete. J Int Soc Sports Nutr. 2014 Feb 27;11(1):7.

• Fothergill E, Guo J, Howard L, Kerns JC, Knuth ND, Brychta R, et al. Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity. 2016 Aug;24(8):1612–9.

• Siervo M, Frühbeck G, Dixon A, Goldberg GR, Coward WA, Murgatroyd PR, et al. Efficiency of autoregulatory homeostatic responses to imposed caloric excess in lean men. Am J Physiol Endocrinol Metab. 2008 Feb;294(2):E416–24.

• Pardue A, Trexler ET, Sprod LK. Case Study: Unfavorable But Transient Physiological Changes During Contest Preparation in a Drug-Free Male Bodybuilder. Int J Sport Nutr Exerc Metab. 2017 Dec;27(6):550–9.

• Levine JA, Eberhardt NL, Jensen MD. Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science. 1999 Jan 8;283(5399):212–4.

• Sardeli AV, Komatsu TR, Mori MA, Gáspari AF, Chacon-Mikahil MPT. Resistance Training Prevents Muscle Loss Induced by Caloric Restriction in Obese Elderly Individuals: A Systematic Review and Meta-Analysis. Nutrients [Internet]. 2018 Mar 29;10(4). Available from: http://dx.doi.org/10.3390/nu10040423.

• Green KK, Shea JL, Vasdev S, Randell E, Gulliver W, Sun G. Higher Dietary Protein Intake is Associated with Lower Body Fat in the Newfoundland Population. Clin Med Insights Endocrinol Diabetes. 2010 Mar 31;3:25–35.

• Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005 Aug;135(8):1903–10.