How is this for a controversial heading?! 90% of you are probably shaking their heads and thinking, is this woman out of her mind? Hasn’t she read anything about weight loss strategies? After all, there are thousands of magazine articles, online health advice pages, blog posts, tv shows and government (!) agencies that say that exercise helps you lose weight. But, please, stay away from the close button on your browser and bear with me for the next few minutes.
Based on my own experience, exercise may help in terms of lifestyle, mind set and emotional release necessary to drop those pounds. But to actually lose weight, you must focus on your diet. Of course, this is just my experience you may say, and maybe I am a statistical outlier. However, there is actually a ton of research saying exactly the same.
And why the official “version” insists on exercise, and not so much on diet, is another debate – I suspect the “food” producing industry has a lot to answer for in this case. I use the term “food” here loosely as some of these products are closer to plastic than things we should put in our bodies for nourishment.
Based on research, here are reasons why you are not losing weight by exercising:
Energy expenditure is not as easily influenced as we believe, it is a deeply hardwired trait in human beings. Studies involving measuring energy expenditure in hunter-gatherer tribes have shown that they don’t burn more energy than an average American or European.¹ It’s not the calorie out variable that makes the difference in body weight between hunter-gatherers and the average Westerner – it’s the calorie in variable. In other words, it’s what and how much we eat.
Now, don’t get me wrong. Exercise is great for health and can help with weight maintenance. Exercise is good for mental and physical health, it keeps us young and happy. It reduces blood pressure, the risk of heart attack, diabetes type 2 and stroke. You can check out this blog post on how exercise keeps you young for example.
But exercise has a very modest effect on weight loss. Do you know the show “The Biggest Loser”? Researchers found that there was no relationship between physical activity and weight loss during the competition. But there was a statistically significant relationship between energy intake (calories consumed) and weight loss. So the contestants that watched their diet lost the most weight, not the ones who exercised the most.² Exercise helped in maintaining the lost weight, but not in losing it.
Everyone “knows” this rule: A pound of human fat represents about 3,500 calories; therefore cutting 500 calories per day, through diet or physical activity, results in about a pound of weight loss per week. Similarly, adding 500 calories a day results in a weight gain of about the same. This is based on a study by Max Wishnofsky from 1958, Caloric equivalents of gained or lost weight. “Wishnofsky’s views of weight change dynamics were based on the limited understanding of fundamental metabolic processes at the time and his simple formulation was framed with impressions gained from short term dieting studies completed in small samples of obese women”.¹
This simple rule of calories in – calories out is too simplistic. Energy balance is an adaptable and dynamic system, and changing one variable influences a whole subset of variables in your body.³
Moreover, the calories you burn when you exercise represent only a small part of your total daily caloric expenditure. The basal metabolic rate accounts for 60 to 80 percent of total energy expenditure, digesting food accounts for about 10 percent. Your total daily activity represents only 10 to 30% of total calorie expenditure. This includes walking to the shops, carrying your groceries, hanging up your washing, walking down the stairs at the office and picking up toys after your children. Any additional activity spent in the gym or running or cycling is a subset thereof (this of course excludes professional athletes).
As a result, it is very difficult to create a calorie deficit through exercise alone. It would take a lot of time to lose a substantial amount of weight. So your much advertised 20-minutes-a-day-workout is not going to cut it (not for weight loss anyway, but it may be very beneficial for your health!). On top of this, most people naturally compensate for additional exercise. After going for a run in the morning, they may take a nap at lunch time. Or because they spend an hour at the gym at night, they spend the rest of the evening on the sofa. Most people “recover” from a workout by sitting more or taking elevators instead of stairs. There is nothing really wrong with that of course. We need rest and time to wind down. But it just shows how difficult it is to change the calorie out variable.
In addition, most people overestimate the amount of calories they burn and tend to compensate with food intake. One slice of pizza can erase one hour on the treadmill for example. And doing a 30 min run does not justify a dessert either. From my own experience I know that I have more appetite when I exercise. After all we need to fuel our bodies so we can perform at our best.
Research also shows that our bodies adapt to exercising: through metabolic adaptations the body tries to fight our effort to lose the weight.
This again confirms what the latest research tells us: Energy expenditure plateaus at a certain point.
In Pontzer’s words “The overarching idea is that the body is trying to defend a particular energy expenditure level no matter how active you get.” *
I hope this research doesn’t discourage you from exercising. As I said above, exercise is vital in so many ways. But if your goal is to lose weight, you must focus on what you put in your body. And exercise for the fun of it.
¹H. Pontzer et al (2012), Hunter-Gatherer Energetics and Human Obesity, in http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040503
² J.C. Kerns et al (2017), Increased Physical Activity Associated with Less Weight Regain Six Years After “The Biggest Loser” Competition, in http://onlinelibrary.wiley.com/doi/10.1002/oby.21986/full
³ D.M. Thomas et al (2014), Time to Correctly Predict the Amount of Weight Loss with Dieting, in https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035446/
* H. Pontzer et al (2016), Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans, in http://www.cell.com/current-biology/fulltext/S0960-9822(15)01577-8