After having successfully lost 10lbs of weight during my current fat loss phase, the instant question I get asked when friends see me getting leaner is, “You must have been doing a lot of cardio. How much cardio are you doing?” Soon their curiosity turns into confusion when I answer them, “None.” They then come to a conclusion either I am genetically “gifted” to lose fat easily or I am lying to them.
In fact, my body is predisposed to put on body fat with no problem if I am not consciously monitoring my weight and if I were to lie I would rather tell them I do more cardio than I am actually doing to make them think I am a hardcore person. Then, what is really going on here? How am I able to lose and maintain a good amount of weight without adding any cardio like the fitness magazines tell us we have to?
In this article, we will take a closer look at scientific evidence that shows why cardio may or may not be necessary in order to lose fat and who can benefit from using other fat loss strategies rather than simply doing more cardio.
What needs to happen in order to lose weight?
The primary criterion for weight loss is a sustained, negative energy imbalance between energy input and energy output. To put it simply, weight loss occurs when one expends more energy than s/he take in from food. And with this weight loss comes fat loss (and some of the weight loss is due to loss of fat free mass).
This negative energy imbalance can be achieved by various means that would lower the energy input, increase the energy expenditure, or do a combination of both. While it is rather straightforward to figure out where the energy input comes from, i.e., food intake, energy expenditure side of the equation entails several components including:
- Resting Metabolic Rate (RMR): The amount of energy our body expends at rest in order to fuel basic functions such as maintenance of vital organs, digestion, hormonal regulation, etc. RMR varies among individuals based on body size, body composition, gender, age, and difference in genetic makeups.
- Thermic Effect of Food (TEF): The amount of energy our body expends in processing the food we eat.
- Thermic Effect of Activity (TEA): The amount of energy our body expends during physical activities such as exercise.
- Non-Exercise Activity Thermogenesis (NEAT): The amount of energy our body expends during involuntary activities other than formal exercise such as breathing, standing, and sitting.
Looking at the model above, cardio would fit in the category of TEA. By doing more cardio, we create greater TEA, which in return leads to greater energy output and causes negative energy imbalance and therefore results in weight loss.
However, as you can see there are lot of other variables we can manipulate to create the same amount of negative energy imbalance. For example, we can increase our RMR by developing more muscle mass, increase TEF by eating more protein, increase NEAT by modifying our lifestyle behaviors, or decrease energy input side of the equation by reducing the food intake.
(Do you want to learn more about how to burn up to 1,000+ calories per day by increasing NEAT? You can find an article here.)
Diet vs. Cardio vs. Diet plus cardio: Which is better at fat loss?
We see from the energy equation that taking in less energy through diet and expending more energy through cardio can both result in weight loss. But is one better than the other? Let’s look at what researches suggest:
- In a 3-month study, there was no significant difference in the amount of weight loss between participants who exercised at a moderately high intensity (78% of max HR) for 45 minutes, 5 days a week vs. participants who dieted alone.
- In a 6-month study that studied subjects who did 50 minutes of cardio, 5 days a week vs. subjects who dieted only, researchers did not find significant difference in the amount of weight loss.
- In another 6-month study, scientists compared two groups of 35 overweight (BMI 25-30) but otherwise healthy adults. The first group was a “diet only group” who reduced their caloric intake by 25% vs. the second group was a “diet plus exercise group” who reduced their caloric intake by 12.5% and increased their energy expenditure through cardio by 12.5%. At the end of six months, both diet only group and diet plus exercise group lost approximately 10% of their bodyweight, resulting in the same weight loss.
By looking at the studies above among many other studies that suggest the similar results, we can infer that you will lose weight as long as you are creating negative energy imbalance, whether the source of the energy deficit comes from eating less or doing more cardio, given that the amount of deficit is matched.
While it is a great idea to engage in regular cardio exercise program to improve cardiovascular and overall health, the common belief that one must participate in jogging, fast walking at an incline, high intensity interval training, or some sort of cardio exercise in order to lose weight simply does not hold the truth. One can simply pay more attention to his/her nutrition and lose weight effectively through diet without additional cardio.
The purpose of this article is not to convince that cardio is useless for fat loss but rather to give you freedom to choose which route you want to take for your fat loss journey: if you enjoy jogging every morning and prefer eating more, then doing cardio regularly can be a good idea. However, if you would rather prefer eating less and avoid having to do cardio, then simply focusing on your diet can be just as effective.