Exercise to Lose Weight? Maybe Not

Submitted By: Amy Sercel MS RD CD

Edited By: Marcia Bristow MS RDN CSSD CD

Often when people have a goal of losing some weight, their first strategy will be to work out more often.  It’s possible that you’ve even tried this in the past.  If so, you might have noticed that exercising more does not always result in the weight loss you want, or may lead to a slight weight gain.¹

The truth is that exercise alone isn’t enough to achieve significant weight loss.  In order to lose weight you need to burn more calories than you eat, which creates something called an energy deficit.  As a general rule, you need a deficit of 500-1,000 calories each day to achieve a healthy weight loss of 1-2 pounds per week.  Unfortunately, the number of calories you will burn through exercise is affected by your age, gender, ethnic background, body mass index, and genetics, so it’s hard to estimate how much exercise you need in order to create enough of an energy deficit to lose weight.²

It’s common to overestimate the number of calories you burn during exercise and underestimate the calories you eat.  Some foods are surprisingly high in calories, and you might not burn as many calories through exercise as you think.  If you weigh 150 pounds, here are some activities you would need to do to burn off different foods:^3,4

• Walk briskly for 30 minutes to burn off a 12-oz beer with 150 calories
• Swim for 1 hour to burn off a bagel and cream cheese with 450 calories
• Run 4 miles to burn off a 16-ounce mocha latte with 400 calories
• Lift weights for 1 hour to burn off 2 tablespoons of Nutella with 200 calories
• Row for 45 minutes to burn off a medium serving of French fries with 365 calories

In addition to taking a longer than you realize to burn off the calories you eat, it’s also possible that your body will make up for the calories you burn through exercise by slowing your metabolism or producing hormones that make you feel more hungry.  In one study, 35 people exercised long enough to burn 500 calories per day for five days each week.  While in theory everyone in the study should have lost weight, half of the participants either didn’t lose weight or gained weight.  These participants reported feeling hungrier than usual and ended up eating an average of 270 calories per day more than they did before starting the program.⁵ Other studies suggest that the number of calories you will burn through exercise levels off as you get more active because your metabolism slows down in response to your increased activity level.^6,7 

Although exercising alone might not be the most effective way to lose weight, it can certainly contribute to the energy deficit needed for weight loss, and there are many other reasons to be active.  Regular physical activity can help prevent further weight gain, and can also reduce your risk of heart disease, diabetes, and some cancers.  It will also help you maintain your balance and muscle mass as you get older and can help keep your mind sharp.⁸ If you are looking to lose weight, create an energy deficit by filling up on low-calorie fruits and vegetables and choosing smaller portions.  Make an appointment with a Registered Dietitian to learn how many calories you should eat every day, develop strategies to make dietary changes that will work for you and set realistic physical activity goals.  This way, you will form healthy habits that will help you lose weight and maintain your weight loss.

References:

1. Liebman B. You should exercise to lose weight, right? NutritionAction.com. November 2016. http://www.nutritionaction.com/daily/exercise-for-health/exercise-to-lose-weight/?mqsc=E3859437&utm_source=WhatCountsEmail&utm_medium=Nutrition_Action_Daily_TipsNutrition%20Action%20Daily&utm_campaign=2016.11.25%20Exercise%20for%20Health. Accessed November 25, 2016.

2. Thomas DM, Kyle TK, Stanford FC. The gap between expectations and reality of exercise-induced weight loss is associated with discouragement. Prev Med. 2015;81:357-360. doi:10.1016/j.ypmed.2015.10.001.

3. Publications HH. Calories burned in 30 minutes for people of three different weights. Harvard Health. http://www.health.harvard.edu/diet-and-weight-loss/calories-burned-in-30-minutes-of-leisure-and-routine-activities. Accessed December 13, 2016.

4. Food Nutrition Chart, Food Calorie Chart, Whats Cooking America. https://whatscookingamerica.net/NutritionalChart.htm. Accessed December 13, 2016.

5. King NA, Hopkins M, Caudwell P, Stubbs RJ, Blundell JE. Individual variability following 12 weeks of supervised exercise: identification and characterization of compensation for exercise-induced weight loss. Int J Obes. 2007;32(1):177-184. doi:10.1038/sj.ijo.0803712.

6. Pontzer H, Durazo-Arvizu R, Dugas LR, et al. Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans. Curr Biol. 2016;26(3):410-417. doi:10.1016/j.cub.2015.12.046.

7. Byrne NM, Wood RE, Schutz Y, Hills AP. Does metabolic compensation explain the majority of less-than-expected weight loss in obese adults during a short-term severe diet and exercise intervention? Int J Obes. 2012;36(11):1472-1478. doi:10.1038/ijo.2012.109.

8. Physical Activity for Everyone: Guidelines: Adults | DNPAO | CDC. http://www.cdc.gov/physicalactivity/everyone/guidelines/adults.html. Accessed June 14, 2015.