Misconceptions of Exercise and Weight Loss

Updated: Jun 22, 2020

Myth #1: Being active is the same as exercise

A common phrase heard by those of us who work in weight loss and obesity medicine is “I exercise all the time, I don’t know why I’m not losing weight.” When asked to describe what kind of exercise they perform, they often mention “walking” or “gardening”. While it is important to move and stay active with activities like walking, in order to enact change a body must be stressed. Merriam-Webster defines exercise as “bodily exertion for the sake of developing and maintaining physical fitness.” Exertion is defined as “a laborious or perceptible effort”.

Wolff’s law and Davis’s law essentially describe a physiologic phenomenon whereby the human body responds to demands imposed upon it. Essentially, exerting repeated stress on a bodily tissue is needed to develop any noticeable change. The body responds to stress by preparing itself to be better suited to handle the stress by adding bone density (impact exercise), muscle mass (resistance training), or red blood cells (cardiovascular training).

Walking is a great activity and may be a good introduction to exercise for an untrained individual, though walking by itself without an incline is not enough exertion or stress to cause remodeling or positive change to body composition, muscle mass, or cardiovascular health. The average American gets 4,774 steps daily [1]. Seeing this, it is a bit ambitious to ask people to get 10,000 steps a day. However, even when this threshold is met, the average person reduced their weight by only 1-2 pounds in an entire year [2]! 1.5 lbs of weight lost in an entire year of walking 10,000 steps everyday is not an efficient use of anyone’s time if your goal is weight loss. Walking and gardening is just not enough exertion to lose weight.

Myth #2: Cardio is better for weight loss

While both cardio and weight training play important roles in improving physical well-being and overall health, the reality is that most of our people have difficulty finding the time in their day to exercise. The average American only spends two hours per week being physically active [3]. Traditionally, we have thought of low intensity steady state (LISS) exercise (AKA “Cardio”) as the primary form of exercise to assist with weight loss. While the energy expended during cardio training often exceeds the energy expended during resistance training, it has been proven that weight loss is greater with resistance training than it is with cardiovascular training. The reason for this is what is known as excess post-exercise oxygen consumption (EPOC), also known as oxygen debt or “the afterburn effect”. After any higher intensity workout, the body needs to take in oxygen at a higher rate to allow for repair. This increases the body’s resting metabolism, so it continues to burn calories at a higher rate than at baseline. An analogy this author often uses with his patients is how a car engine stays warm for hours after a long drive before it gradually cools to a normal temperature.

Exercises that utilize the anaerobic energy pathway during a workout increase the need for oxygen during recovery, thereby enhancing the EPOC effect. This can be achieved with circuit training and heavy resistance training with short rest intervals.

So while the calories burned during the actual exercise session are important, the afterburn effect raises the metabolic rate for an extended period, burning more calories over time. Of all forms of exercise, high-intensity interval training (HIIT) is the most effective for increasing post-workout caloric burn. While EPOC varies by the individual, typically it can be increased for a few hours after a cardio workout to beyond 24 hours after resistance training. EPOC after HIIT training can be increased for up to 48 hours [4].

Perhaps the most important piece of advice busy Americans who have trouble finding the time to exercise, is that you can get regarding high intensity interval training, EPOC is influenced by the intensity of the exercise, not the duration. A meta-analysis has shown that HIIT required 40% less times commitment than moderate intensity continuous training (MICT) for the same results [5].

Of course, resistance training is also beneficial in increasing muscle mass. Muscle is metabolically active, therefore having more muscle means that an individual will have a higher resting metabolic rate. Lean muscle mass requires more energy to maintain itself than fat, so resistance training can be dually beneficial in increasing EPOC as well as increasing muscle mass to a greater degree than cardio training.

However, the most important thing to remember is that consistency of exercise is what matters. If someone can find a form of physical activity that they enjoy and perform regularly, this is always better than a sedentary lifestyle.

Myth #3: “If I lift weights, I will get bulky. I don’t want to look like a man!”

This myth is heard by many personal training specialists from women who are afraid that if they lift weights they will get “bulky”. Women will indeed gain muscle mass by lifting weights. However, in the absence of testosterone to trigger nitrogen retention, the growth is significantly less than that seen in men. Resistance training has been shown to cause an increase in growth hormone in men and women, though it was significantly raised in men, and barely increased in women. Serum testosterone increased only in men after resistance training [6]. Lifting weights may equate to body building in men, though in women it is body shaping.

Lastly, if you are training to lose weight, then you will need to decrease your caloric intake. While some muscle can be gained in a calorie deficit, to gain the muscle of a bodybuilder an excess of calories is needed.

by Garrett A. Soames, PA-C