When I first got into exercise it was after four sedentary years in university. I had stopped playing sports, stopped doing ballet, and lost some of the little muscle I did have. I started back into activity the way many people do; with running and cardio classes. Although I wish I could say that my intentions were mainly to improve my mental and physical health, I mainly wanted to look more “defined”.
Imagine my confusion, after working out almost every day for months, when my body looked almost the same, despite my fitness level increasing significantly.
So what gives? Why do people often perform a lot of cardio that results in hundreds of calories burned but not see commensurate weight loss?
A recent study adds to a body of literature that suggests that cardio exercise alone may not be the most effective route to fat loss. In this article, I’ll explore the findings from this study and discuss how we can apply them to our own training.
Effect of Aerobic Exercise-induced Weight Loss on the Components of Daily Energy Expenditure, was published in the October 2021 issue of the journal Medicine and Science in Sports Exercise. This study was designed to accurately track calorie expenditure over 24 weeks for people engaging in cardiovascular exercise.
42 study participants were divided into three groups:
- Healthy control group
- Cardio exercise group who expended 8 kcal·kg-1 of body weight per week (800-1000 cals)
- Cardio exercise group who expended 20 kcal per kilogram of weight per week (2000-2500 cals)
Both exercise groups performed 3-5 workouts per week.
Explaining the Results
So why is this the case?
There are a number of possible explanations, including:
- Subsequent decreases in NEAT (non-exercise activity thermogenesis) – meaning you unconsciously move less throughout the day to compensate for this activity. Annoying, I know.
- Likely increase in food intake from increased hunger (although the degree and amount will differ from person to person)
Additionally, people who engage in a lot of cardiovascular exercise, are eating in a calorie deficit, and don’t do resistance training are at more of a risk of losing muscle mass.
Not only is this a bit of a bummer if you’ve worked hard to gain muscle, when people regain lost weight their body tends to gain until they’ve gained back this lost muscle and often results in body fat overshooting (https://pubmed.ncbi.nlm.nih.gov/31950141/). Muscle loss during a diet is more extreme when the dieter is not engaging in resistance training, not eating enough protein, is not sleeping enough and/or psychologically stressed (https://pubmed.ncbi.nlm.nih.gov/20921542/).
The Take-Home Message
Cardiovascular exercise and resistance training both have a myriad of benefits and in my opinion, both belong in your training routine. While I don’t often discuss or push intentional weight loss, I do understand it’s a goal for many.
As it is very challenging to maintain weight loss, one of the worst approaches for long term sustainability is to engage in excessive cardio, especially while drastically cutting calories. It’s also a recipe for frustration if it increases your hunger so you’re not eating in a deficit.
This is not to dissuade you from doing cardio. Cardiovascular exercise is important to include for your health. However, relying solely on this type of exercise for your body recomposition goals is not the most effective approach.
Do your best to get in a minimum of two resistance training sessions/week and two cardio workouts. You’ll strengthen your heart, build/maintain muscle mass, strengthen your bones and joints, and benefit your brain and mental health.
If you focus on weight loss, cardio will likely help a little but instead of adding in tons of it and relying on that for creating a deficit, focus instead on increasing your movement throughout the day (NEAT). Not only does this add up substantially, it doesn’t require recovery and doesn’t tend to increase your appetite.
If you’re looking for non-calorie tracking dietary tips, check out the “Non-tracking nutrition strategies” video on the Crewe Fitness app in the nutrition section.
Broskey NT, Martin CK, Burton JH, Church TS, Ravussin E, Redman LM. Effect of Aerobic Exercise-induced Weight Loss on the Components of Daily Energy Expenditure. Med Sci Sports Exerc. 2021 Oct 1;53(10):2164-2172. doi: 10.1249/MSS.0000000000002689. PMID: 34519717; PMCID: PMC8441008.
(plus the two others I linked above)