I think that weight loss is the number one reason that people start CrossFit, at least at our gym. Most people have the same story: they used to work out and/or play sports and got out of the routine. They come in to the gym looking to get back in shape and lose a certain amount of weight, and inevitably the question comes up. Why do we lift weights so much? If I am trying to lose weight then shouldn’t I be doing more cardio? I want to answer that question now and explain why we lift weights and why we put so much value on muscle, as well as why muscle is so important in the long run.
1. High intensity strength training burns more calories than cardio
CrossFit defines intensity as average power. Let’s take a quick step back into physics class and talk about power. Average power is equal to force times distance over time (P=FxD/T). This means that you can increase average power (or intensity) by increasing force output, increasing the distance, or decreasing the time. In simpler terms, if we can do more work in less time, then we are increasing power, and therefore increasing intensity. Since there are two inputs into the formula (force and distance), there are several ways we can achieve higher power. We can increase the weight (think a heavy squat set) or we can lower the weight and do it a lot of times to increase the distance the weight travels (think a barbell thruster). However, the longer the duration of effort, the lower power output will be (think long steady cardio).
Now that we have defined intensity, we need to talk about why it is important for weight loss. When you put your body through a high intensity workout, it literally thinks you are trying to kill it. Your body is going to make changes so that the next time it encounters this situation, it is better prepared to handle it. When you you finish a high intensity workout, your body immediately starts to make adaptations. That is why your heart rate will remain elevated and your metabolism will be higher (burning more calories) hours after your have finished your workout. Compare this to a steady stated cardio session where power output is much lower. The body will be able to adapt to this very quickly once the session is over and will be back to normal much sooner than a high intensity session. If you have lifted weights during the high intensity session, then your body will have to repair and rebuild the muscles used so that they are stronger. This repairing will also burn calories. As a person becomes more fit (can do more work in less time), their body makes more and more adaptations. The sum of these adaptations over time is more calories burned and, as a result, more fat burned.
2. Muscle burns more calories throughout the day than fat
We all have that friend who seems like they can eat whatever they want and not gain a pound. Genetics definitely plays a part in this, but odds are this person also has a very high percentage of muscle compared to body fat. Studies vary on the actual amount, but there is a consensus that a pound of muscle requires more calories throughout the day than a pound of fat, with some studies saying muscle requires twice as many calories as fat. This means that if two people sit on the couch all day doing absolutely nothing, then the one with the more muscle mass will burn more calories.
Let’s apply this knowledge practically. If we take two people who each want to lose ten pounds and put them on two different programs, then we might get two different results in the long run. Let’s assume that they do not change their diets at all and take in the same amount of calories every day. If one of these people loses the weight through steady cardio, then they have not built any extra muscle. They have not made a permanent change to their metabolism, and if they quit doing the cardio and continue to take in the same amount of calories then they will put the weight back on quickly. However, if the other person loses the ten pounds through high intensity strength training, then they have also added muscle to their body. If they quit working out and continue to take in the same amount of calories then they will put some weight on, but it will be at a much slower rate because their metabolism has increased due to the increased muscle mass.
3. Muscle increases overall health
There are numerous studies citing the benefits of muscle to overall health. Some of these include enhanced brain activity, lower rates of cancer, and even longer life expectancy. These are all great benefits, but they do not address the topic of this article. It is my contention, however, that a healthier person is a more active person. Generally speaking, a healthier person feels better throughout the day. A person who feels better throughout the day is more likely to partake in physical activities such as sports, get outside to play with their kids, or even take the stairs to the second floor instead of taking the elevator. The sum of all of these activities over the long term is more calories burned, and, as a result, less body fat. Increased muscle mass can also protect the bones and joints from a trauma (car accident, trip and fall, etc.) that might cause a person to be immobile for a long period of time, leading to weight gain. Finally, increased muscle mass can take the stress off of aching joints caused by arthritis or wear and tear, leading to a person more likely to feel better throughout the day and be active.
In summary, muscle is, in my opinion, the most important aspect of weight loss in the long term. A quick three month crash course diet or cardio fest might bring about short term weight loss, but the best long term option is to develop muscle. After all, the average life expectancy in the United States is almost 80 years. We should all be planning accordingly.