Want to Lose Weight? Stop Exercising

Dr. Tzvi Doron
February 27, 2018

Want to Lose Weight? Stop Exercising

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More than 1/3 of Americans are obese, and obesity is linked to type 2 diabetes, stroke, heart disease, and even certain types of cancer. So it’s no surprise that “weight loss” is a multi-billion dollar industry in the US. But despite the hundreds of fad diets and exercise trends sweeping the country, we’re no closer to a solution to the obesity epidemic straining our healthcare system. And the problem is a simple misunderstanding about diet, exercise and weight loss.

Exercise doesn’t help you lose weight

Bad news, America. Exercise isn’t the key to weight loss—diet is. You can’t just eat whatever you want and take a spin class to “burn it off.” Your body doesn’t work that way. While exercise is absolutely essential to overall health (and happiness!), it has almost nothing to do with weight loss. We have a fundamental misunderstanding about how our bodies use food, and the importance of diet. But don’t trust me. Let’s look at the science behind calories, energy use, and weight loss to understand why exercise isn’t the key to losing those last 10 pounds. If you want to lose weight, it’s time to get real about what you put into your body.

What is a Calorie?

Millions of people “count calories” as a foundation to their weight loss plan, but do you know what a calorie actually is? Sure, you probably know that the USDA recommended daily allowance for a female adult is roughly 2,000 calories (it’s 2,500 calories for men). But what does that actually mean? What the heck is a calorie?

Science warning: Don’t panic. This will only take a second.

A calorie is a unit of energy. That’s it. It gets complicated quickly, but for the purpose of this article everything you eat has an amount of energy stored in the chemical bonds that hold that food together. When you digest that food, you break apart these bonds and turn the food into energy that you can use. That’s the magic of digestion. And every food is different.

Sugars and starches have different energy levels than saturated fats or proteins. Also, certain foods are tougher for your body to break down (I’m looking at you complex carbs). Regardless, everything has a caloric value—or total amount of energy. We use this measurement (it’s called “large calories”) to track the amount of energy in food. And the equation for a calorie is actually pretty simple.

A (food) calorie is the amount of energy it takes to raise the temperature of 1kg of water, 1°C

A large calorie is the amount of energy needed to raise the temperature of a 1kg of water 1°C. Sorry for the metric system, Americans. Just picture how long you’d have to boil a large pot of water on the stove to get it to warm up. That’s a good way to imagine what your body does with a few calories. Except instead of a pot of water it’s a big ol’ person. And it’s not just 1° increase, it’s 98.6°F all day everyday.


Now think about how much energy is stored in 2,000 calories. That’s a lot of boiling water. Picturing calories as a steady heat source—like a stove top warming water—is a great first step to understanding how your body uses calories everyday. Because the bulk of our calories go don’t go toward physical activity.

Metabolism and Weight Loss

Exercise is actually pretty useless when it comes to losing weight,” argues Vox senior health correspondent Julia Belluz.  Belluz bases her findings on over 60 weight loss studies, but you don’t have to be a health science expert to see why exercise isn’t the answer when it comes to weight loss. All you need is simple math.

You only burn about 20% of the calories you eat during physical activity (aka exercise). Obviously, that number fluctuates depending on your lifestyle and habits—cycling burns more calories than sitting at a desk. But the difference isn’t very much. In fact, the lion’s share of your metabolism (total energy used to function) doesn’t have anything to do with exercise at all.

Roughly 80% of every calorie you eat goes to digesting your food, maintaining that toasty 98.6°F body temperature, and supporting basic bodily functions. This huge slice of the calorie pie is called your Basal Metabolic Rate (BMR), and it refers to the number of calories you need to survive. And you have almost no way to influence the way your body uses the majority of calories everyday.

Exercise only burns about 20% of your daily calorie intake

Even if you somehow double the number of calories you burn from exercise (which is really tough to do), it’s still nothing compared to the calories your body burns just to keep you warm and breathing. What does that simple fact mean for weight loss? Weight loss isn’t about how much you exercise—it’s about how much you eat. Here are five simple diet strategies to help you get off the treadmill (pardon the pun) of disappointing weight loss results.

Weight Loss Secret #1: Smaller Portion Sizes

The amount of food you eat isn’t really up to you. No, really. Study after study has shown that the biggest predictor of how much you isn’t your hunger, your diet plan, or your willpower. It’s the size of the portion in front of you.

People eat more food when the portions are larger

Portion size is a subconscious visual cue that tells our brain what to expect from a meal. It’s built into not only our biology, but also our culture. “Finish your plate,” your mother or grandfather may have told you as a child—which is a great way to get kids to eat their veggies. But what happens when the portion sizes keep getting bigger, and the food on the plate isn’t carrots and broccoli?

If you have a 3 oz portion of potato chips, you may eat only 2 oz. Whereas if you have a 5 oz bag you’ll eat 3.5 oz under the same circumstances. “Once you pop, you can’t stop,” right? One Cambridge University study found that people were “reluctant to leave a plate with food on it.” They also found that “smaller plates, glasses and cutlery helped people eat less.”

Eating larger portions of less healthy foods is a driving force of the obesity epidemic. Take back control of your portion sizes with a smaller plate, and resist the temptation to buy the bigger sized item because it gives you more value for your money. The first step to weight loss is portion control.

Weight Loss Secret #2: Meal Replacements

If you haven’t heard about soylent, prepare to be weirded out. This groundbreaking “meal replacement” drink is loaded with all the calories, vitamins, and nutrients you need to survive—without food. And while it’s not technically marketed as a full-time food replacement, it’s pretty close. In fact, dozens of articles of athletes and everyday people have written about their experiences completely replacing food with soylent for up to 30 days.

While those examples are the extreme, meal replacement (MR) drinks are one of the rare dietary trends that actually has some scientific evidence to back up the weight loss claims. These drinks are typically high in protein and low in fat and calories, and can replace one or even two meals a day. They come in ready-to-drink formulations (e.g. slim fast) or protein powders that can be mixed with water, milk, or juice. Some athletes add a scoop of peanut butter for more protein. Others rely on the extra calories from mixing it with juice or milk to make it a satisfying smoothie. However you use MR, the results are interesting.

One of the main reason MR drinks help you lose weight is the ease. Planning healthy meals is hard, especially if your life is already hectic. Taking the pressure of for one or two meals a day can replace fast food or a hastily eaten sugary snack with a meal that has a fixed amount of protein, carbs, fat, and calories. If you’ve been struggling with your weight, give yourself a crutch. I recommend using meal replacement drinks or powders for at least a couple of months to see if it helps.

An easy way to start is replacing one meal per day with an MR on work days—breakfast or lunch—and eating regularly on the weekends. #cheatday You can always add more meals per day and/or weekends if it’s working well for you.

Weight Loss Secret #3: Track What You Eat

It may seem obvious, but tracking what eat is a great way to lose weight. In fact, research clearly shows that people who regularly track their food intake, weight, and exercise are more successful with weight loss than those who don’t. I often saw with my patients that this one intervention alone was sort of “magical” in the sense that when people start tracking what they eat they automatically lose a bit of weight.

I don’t know why it works. It could be that making people more aware of their habits motivates them to make better choices. Especially when they have record what they’re eating (and show their doctor!). Another possibility is that the accountability of reading over their logs later makes people make better food choices. Either way, I highly recommend tracking as many of these variables as possible without making life too crazy.

And with the number of food tracking and fitness apps available today, you have no excuse. If you’ve been trying to lose weight or even maintain your weight and haven’t tried self-monitoring, I highly recommend these three food tracking apps:

  • My Fitness Pal — My Fitness Pal is focused around creating weekly dietary and exercise (ha) plans to help you hit specific weight loss goals
  • Chron-o-meter — If you want to get granular with your calorie tracking, welcome to your new favorite app
  • Calorific — This lets you see the calories in food, even without a nutrition label

Weight Loss Secret #4: Avoid Sugary Drinks

One of the foods that’s most consistently associated with obesity, type 2 diabetes, and even cardiovascular disease is sugar sweetened beverages (SSBs). SSBs include things like regular soda, fruit punch, and sweetened tea. It also includes things that may not be quite as obvious. Triple mocha frappucino, anyone?

One can of coca-cola has 39g of sugar

I usually even recommend that my patients cut back or eliminate fruit juice as this is also a source of liquid calories that are consumed very easily and don’t satisfy hunger well. If you need to wean yourself off SSBs, try drinking diet soda or mixing your juice with one part water for every part juice in the beginning and slowly eliminating SSBs over time completely. You can similarly decrease sugar in your coffee slowly over time.

Weight Loss Secret #5: Decrease “Overly Delicious” Food

Everyone wants food to taste good. But what happens when your food tastes too good? Scientists call this type of food “hyper-palatable food,” and it basically means food that tastes way better than anything you could ever find in nature.

For example: I think a regular baked sweet potato tastes great, but it can’t compare to the perfect mix of sweet, salty, and crunchy you get from BBQ potato chips. The problem is that these hyper-palatable foods taste so good (to your brain) that they encourage you to overeat.

I recommend that you keep these kinds of foods to no more than 10% of your total food intake. If you’re trying to lose weight, restrict them even more. I’m not gonna lie to you, it’ll be tough. But hyper-palatable foods typically contain way more calories than “regular” food. Cutting out just a few of these “guilty pleasures” can make a significant difference to your health and your waistline.

The Problem with Counting Calories

Here’s the thing about weight loss and the 2,000 calorie guideline. It’s just a guideline. Everyone has a different BMR and you might processes food differently than your skinny co-worker scarfing Pringles next to you. That’s life. If you bike to work, you’ll use more calories than someone that commutes in their car, sits at a desk all day, then watches Netflix at night. Daily calorie demands can vary wildly, so sticking to that 2,000 calorie limit is misleading.

Elite athletes can burn 9,000 calories a day

Elite athletes can burn thousands more calories a day, while elderly people need significantly fewer calories thanks to a slower metabolism. But there’s another problem with the calories on nutrition labels. They don’t actually reflect what the amount of energy you’re really getting.

Calorie Labels are Misleading

Nutrition labels show the number of calories in the food you eat. However, that number doesn’t reflect how much energy you actually get out of the food once you digest it. The act of breaking down food and turning it into the starches and sugars your body can actually use requires some energy (about 10% of your daily energy usage), so everything you eat “costs” you energy to process. However, fibrous foods like vegetables or celery take a lot more energy to break down than something like a sugary soda. Calories also don’t show how your body uses things like proteins, vitamins or essential amino acids. It’s simply a reflection of total energy.

The fact is, what you eat matters a lot. Natural foods, small portions, and tracking your diet will help you lose weight. If you can avoid sugary drinks and replace the occasional meal with a nutritious MR supplement, you’ll fare even better. Losing weight is hard enough without feeling defeated that your workout plan isn’t getting results. Diet is more important than exercise when it comes to shedding those extra pounds. Rethink the food that hits your plate before you hit the gym.

Geek Out: More Weight Loss Resources

Not enough info for you? No problem. Nerd out on diet and weight loss with research from the most trusted sources on the interwebs. If you have any questions or you think we missed something important, leave a comment or book a consultation with one of these trained professionals and we’ll get you on the way to a healthier manhood.

  1. Fructose and Cardiometabolic Health
  2. The Influence of Palatable Diets in Reward System Activation
  3. Self-Monitoring in Weight Loss
  4. CDC Adult Obesity Facts
  5. Effect of a conventional energy-restricted modified diet with or without meal replacement on weight loss and cardiometabolic risk profile
  6. Meal Replacements for Weight Loss in Type 2 Diabetes in a Community Setting
  7. Use of a Computerized Tracking System to Monitor and Provide Feedback on Dietary Goals for Calorie-Restricted Diets

This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Dr. Tzvi Doron is board certified family doctor and the Clinical Director of Roman. He’s a member of the American Osteopathic Association (AOA) and the American Academy of Family Physicians (AAFP).

Dr. Tzvi Doron

Dr. Tzvi Doron is board certified family doctor and the Clinical Director of Roman. He’s a member of the American Osteopathic Association (AOA) and the American Academy of Family Physicians (AAFP).

All stories by:Dr. Tzvi Doron

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Dr. Tzvi Doron

Dr. Tzvi Doron is board certified family doctor and the Clinical Director of Roman. He’s a member of the American Osteopathic Association (AOA) and the American Academy of Family Physicians (AAFP).

All stories by:Dr. Tzvi Doron