Does Cardio Make You Fat?

A lot of people when first tasked with weight loss or body sculpting immediately head for their running shoes to pound the pavement. While it is well known among the fitness industry that cardio isn’t exactly the best solution, all the scientific terms thrown around may be a little overwhelming, so here we’ll explain in layman terms the relation between fat loss (we say fat and not weight because that’s what you want to lose!) and the various types of exercise.

1. Aerobic exercise (running, cycling, jumping rope, star climbing), is most effective when if you are overweight and new to exercise. 

For someone who has always been sedentary, getting up and moving will allow them to learn to switch between fat burning and carb burning, an adaptation which is highly beneficial to fat loss. In addition, insulin sensitivity improves and your body uses the sugar in your blood much more effectively. 

However, as you get fitter, your body becomes more efficient and will require less calories to sustain the same energy expenditure, which means that to get the same amount of metabolic benefit, you will either have to increase intensity or increase the distance. For example, scientists estimate from calorie balance equations that it would require upwards of 1 hour of moderate-intensity cardio 7 days a week to produce continual fat loss to the tune of about 1 pound a week in active individuals.

Even this enormous volume of exercise will lead to diminishing returns in the long run because muscle mass will be lost. Plus, the repetitive exercise stress could lead to altered hormone balance, which has further implications which we will discuss below. 

2. Too much cardio can lead to increase appetite – which leads to fat gain

Cardio increases your appetite – this is a physical as well as emotional response. In fact studies have shown that most people end up eating 100 calories more than they just burned off. So you think it’s fine I’ll cardio and watch what I eat, the next point addresses that.

3. Doing cardio together with caloric restriction leads to weight cycling

People initially lose fat and muscle. Muscle is active tissue that burns 6 calories/per lb per day. Fat, on the other hand, burns only 2 calories/per lb per day. Caloric restriction is also a sure fire way for you to burn your precious calorie burning muscle that maintains your all important basal metabolic rate.

Caloric restriction is also highly unsustainable and when you stop dieting and increase calories, not only do you gain the fat back, you also replace the lean muscle that was lost with fat. This is a worse body composition, which means their body will burn fewer calories at rest, and it increases disease risk.

4. Doing too much cardio will actually put you at a higher risk of heart disease

Deviating slightly away from fat loss, excessive cardio actually puts you at a higher risk of heart disease. A recent study in the Journal of Strength and Conditioning Research found that cardio cuases immense oxidative damage and a flood of free radicals to the body.Free radicals are molecules that cause rapid aging in your body. During your “healthy” cardio routine your body is filled with free radicals which cause damage to your organs, damage your skin and not only make you look older but actually do make you get older faster!

For example, people who do cardio with repeated diets in the hopes of losing fat have more inflammation and a higher risk of heart disease than people who don’t diet or exercise and remain the same weight.

5. High cortisol combined with cardio produces changes in the body making fat gain more likely

 Doing cardio also puts massive amounts of stress on your body. It causes your body to release high levels of cortisol, which is a stress hormone.  Here’s what happens when cortisol is high all the time:

•    Cells become resistant to insulin, causing inflammation, and making body unable to access body fat to burn for energy.

•    The hormones that regulate hunger can become imbalanced. Compared to people with normal cortisol, people who suffer more stress and have high cortisol have 15 percent higher ghrelin, which triggers hunger, and 15 percent lower leptin, which suppresses hunger.

•    High cortisol makes people favor high-sugar foods to replace the neurotransmitter serotonin, which is depleted during chronic stress.

•    Growth hormone (GH) and testosterone (T) are suppressed, which is associated with fat gain, particularly in the belly and trunk area.

 In normal circumstances this is not a problem and the cortisol release will be transient. Remember, healthy, sedentary people who start to do cardio will improve insulin sensitivity and fat burning. They are likely to lose some fat as well.

 But, combine the cortisol spike from daily cardio with an elevated cortisol curve due to stress, and you have a fat trap. This is most likely to happen with higher intensity or longer duration cardio workouts. One study even suggests that if you jump out of bed every morning at the same time to go for a run, your body knows what to expect and begins to stress out, releasing cortisol and hanging onto fat, before you even start your run.

6. Cardio interferes with muscle building

 As mentioned earlier, to keep fat off and to get that lean physique you really want to increase muscle mass. Scientists believe aerobic type cardio “turns off” muscle building pathways and promotes catabolism, inhibiting muscle development. Therefore, if you’re trying to build muscle, which is absolutely the best plan for reducing body fat and keeping it off, don’t do steady-state cardio. 

For weight loss, strength training is a superior form of exercise that will allow you to be satisfied with your physique. It optimizes lean muscle mass, elevates metabolic rate, and improves insulin sensitivity. It also improves hormone balance, reduces inflammation, and supports cardiovascular health. 

7. Anaerobic cardio is better for you

 So now that we have radically redefined the way you look at cardio, what kind of cardio activity should we be doing then? Anaerobic cardiovascular! These include high intensity training (HIIT), such as sprints and circuit training, and even more moderate intervals activities (like Pilates!) are all better choices for fat loss than steady-state cardio. 

•    You burn more calories in less time. Depending on how hard you push during the intervals, you can burn more calories in just 25 minutes than you can in double that time when doing cardio. 

•    You experience a more robust energy expenditure in the 24-hour post-workout recovery period than with cardio because your body requires a lot of extra energy to restore metabolic balance and remove waste products.

•    Genes involved in protein synthesis (muscle building) are turned on and you will be more likely to experience a better hormonal environment post-workout, with an elevation in GH and testosterone along with cortisol. This allows interval training to sustain lean muscle mass and may even build muscle for a better metabolic rate.

Summary

After all that scientific spiel, you’ll be curious as to how this will apply to you.

1. If your goal is fat loss, prioritize diet, strength training and stress management. Add in some form of intervals to accelerate results.

2. If your only goal is to build muscle, avoid cardio completely. Focus on putting your energy into lifting and strongman workouts. Prioritize diet and recovery.

3. If you are passionate about endurance exercise but need to lose fat, replace some of your steady-state cardio workouts with moderate-intensity intervals. Add strength training to your activities.

4. If you are training for an endurance race and want to improve performance, do a strength-type lifting program with heavy loads in order to optimize body composition.

5. If you are a power athlete, avoid cardio because power is the performance variable that is MOST compromised by steady-state cardio—much more than strength or hypertrophy.