1 – When you do a cardio exercise, like running, you burn calories from muscle and fat. The body cannot pick to burn the calories that you would like to see burnt, and thus by running you actually decrease your muscle mass. You don’t want to do that because muscles are more metabolic and burn more calories.
2 – Too much cardio exercises increase the production of a stress hormone called cortisol, which leads to bigger food cravings because your body wants to overcompensate for the burned calories. So, you end up consuming more calories than you have burned.
**Too much cardio exercising makes you leptin-resistant, which is the same hormonal effect as sleep deprivation. That way your body is unable to tell if it is full. You get very hungry and eventually develop insulin resistance due to the high amounts of cortisol and you get back to weight gaining.
**Cardiovascular exercises can have negative impact on the thyroid function. In order to have a properly functioning metabolism, the thyroid produces a hormone called T4, which then is converted to T3 to help the metabolism. But, by creating too much cortisol in your body, the thyroid is unable to produce T4 and you end up with dysfunctional metabolism, decreased ability to burn fat and loss of energy.
3 – It is believed that running has a low impact, plus the further you run the more you bang your feet into the ground. If you are overweight this can be bad for your knees and other joints.
Summary: Cardio can cause the reduction of the muscle mass, less efficient metabolism, hormonal imbalance, which can lead to more weight, and it can have a negative impact on your knees if you are overweight.
Walking on the other hand can be a much healthier and more balanced alternative, even though it doesn’t provide the same amount of calorie burning effects as running. By walking you decrease the amounts of cortisol, which is much better on longer term. Walking makes you more sensitive to insulin, which then enables better calorie burning from other exercises and it doesn’t create cravings and unmanageable hunger. It also produces serotonin and dopamine which make you feel motivated and happier and lead to overall wellness.
So, walk as much as possible! Take 30 to 60 minutes walk at least three days a week, and increase this up to six days. Choose walking instead of cardio, and do other activities that relieve stress to the body. But, if you want a firm and good looking body, do some weekly metabolic resistance exercises for 20 or 30 minutes. Couple this with a well-though diet and you won’t have to run ever again.