Lifting weight to lose weight may sound crazy to you at first, and you’re not alone. To many people, common sense says that cardio is the only way to burn fat while lifting weights makes you bulky. By the end of this article, you’ll come to see that this couldn’t be further from the truth. Yes, cardio does burn calories, but lifting weights may have even more benefits in regards to weight loss!
First, let’s dismiss a common myth. Lifting weights will not make you bulky! You won’t go to bed looking like Spongebob one day and wake up looking like Arnold Schwarzenegger the next! If lifting weights really made you instantly gain weight, don’t you think that every guy in your local gym would look a lot bigger and have to work a lot less hard? Gaining muscle is a painfully slow process, and if you ever do feel “too big” it’s a pretty simple fix! Just stop lifting for a while! Stressing about accidentally getting “too big” is like stressing about accidentally winning the Olympics. It only happens with years of dedication and training, not by accident.
With that out of the way, let’s dive into fat loss. Fat loss occurs when you burn more calories than you consume, creating a caloric deficit. This deficit can be made greater by decreasing the amount of calories eaten, or by increasing the amount of calories burned. This is where cardio comes into play as it is a simple way to increase the amount of calories burned. Many look to cardio as the best way to burn excess calories due to the fact that a specific time of cardio will likely burn more calories than lifting for that same amount of time would. Logically, this makes sense. In 20 mins of jogging, you’re moving constantly; whereas 20 minutes of lifting is broken up into several sets and rest periods so that actual exercise occurs during a fairly small amount of that 20-minute time span. However, the main benefits of lifting don’t actually occur during exercise!
Lifting is extremely beneficial for weight loss due to its post-exercise effects, specifically its ability to help maintain or gain muscle mass, and its ability to boost EPOC (excess post-exercise oxygen consumption). Let’s start with gaining or maintaining muscle mass. This is extremely beneficial for weight loss because muscle burns more calories than fat! This means that more muscle leads to a higher metabolism. As a large caloric deficit without resistance training will typically result in muscle loss, even just being able to maintain your muscle mass is extremely helpful!
The next fat loss benefit of lifting weights is the boost in EPOC that it creates. Increases in EPOC cause increases in calories burned as your body takes up increased amounts of oxygen to recover from the oxygen deficit that was created during exercise. Both resistance training and HIIT (high-intensity interval training) cardio have been shown to cause significantly higher amounts of EPOC than steady state cardio (1). All three exercise routines took about 45 minutes each to complete, with the HIIT cardio including 2-3 minutes of rest between each interval. This puts a dent in the big selling point of HIIT, which was that it burns more calories in less time. While the program used in this study required less time spent actually exercising, the full HIIT program (including rest times) took the same amount of time as the steady state cardio program. This study essentially shows resistance training to be superior to steady state cardio, and just as beneficial as HIIT training in respect to EPOC.
Knowing that the previously mentioned study showed HIIT cardio and resistance training to boost EPOC about evenly, you may be thinking that there’s no need for resistance training. While these two forms of exercise were shown to increase EPOC equally in this study, they are hardly equal in terms of practicality. First off, HIIT cardio is extremely difficult to perform in a typical commercial gym. You’ll probably see a few people attempting to do so, and many do successfully! Attempting to do HIIT on a treadmill is not ideal because you cannot immediately accelerate into a full sprint during the high-intensity interval. Doing sprints in the gym is a great option if space is provided, however, you’d have to run back and forth in a relatively small space for 45 minutes just to get the same benefits as you’d get from 45 minutes of weight training! Even doing HIIT outside has its problems due to the demand it places on the body. 45 minutes of steady state cardio is nothing out of the ordinary, but you’ll rarely see people doing HIIT for a full 45 minutes because of this demand. Resistance training is also much more applicable to the general public because the fitness level that is required to complete 45 minutes of HIIT is much higher than that which is required to complete 45 minutes of resistance training because weights and rep schemes can always be scaled from person to person. On top of this, weight training also has the previously discussed benefit of increasing muscle mass (and thus your resting metabolism). This is not to say that HIIT and steady state cardio should be written off completely. Both can be extremely beneficial components of a complete exercise program! However, no form of training can replace resistance training in terms of applicability, practicality, and total metabolic increase. Cutting out resistance training to avoid getting “too bulky,” would mean cutting out the form of training that has the most potential benefits in relation to fat loss.
Criticism of Resistance Training for Weight Loss
It should be noted that a 2012 study from Duke University showed cardio to cause more fat loss than resistance training or a combination of the two (2). This study found that the group performing resistance training alone actually increased fat mass. The combination group did lose some fat mass, but not as much as the group performing cardio alone. However, more research is needed. It does not make sense to cut out resistance training based on the results of one study alone, especially when the experimenters themselves do not recommend skipping resistance training. They state “a program including RT (resistance training) is needed for increasing lean mass in middle-aged, overweight/obese individuals.” Essentially the researchers are saying that resistance training is needed to counteract sarcopenia (age-related muscle loss). I would argue that resistance training is also needed for a younger population looking to lose weight, as it allows you to build up increased muscle mass before sarcopenia even begins. This puts you in a better position to keep the weight off long-term, which should always be the end goal. The study also has some potential flaws in terms of the form of resistance training used, as well as the limited number of subjects (only 199 participants). The study states “The resistance training groups were prescribed three sessions per week, three sets each session of 8–12 repetitions, designed to target all major muscle groups.” It also says that only 1 set was used for the first 2 weeks, 2 sets were used the second 2 weeks, and that the total 3 sets were not built up to until week 5. This training hardly sounds like enough volume or intensity to cause muscular overload, likely explaining the lack of hypertrophy (muscle gain) or boost in EPOC. The RT groups also showed increases in LBM (lean body mass) that did not occur in the AT group. This will lead to a higher metabolism over time, further helping to keep the weight off. The combination group was also shown to cause a greater decrease in total body fat percent due to the simultaneous increase of LBM and decrease of fat mass. The combination group also had a greater reduction in waist circumference! Although this study has been shared in numerous articles arguing that cardio causes more fat loss than a combination of cardio and resistance training, it is important to realize that this is a somewhat skewed phrasing. Yes, the results did show the greatest reduction in fat mass to come from the cardio-only group, however, the greatest decrease in body percent came from the combination group due to their simultaneous increase in LBM and decrease in fat mass. Given that most people are trying to change the overall appearance of their bodies rather than just the number of pounds of fat, this is likely a more important statistic to focus on for many people! While the group of 119 participants is a relatively small sample size to draw any absolute conclusions from, either way, the results of this study show are widely misinterpreted by the media. While many articles focus on the results showing that cardio alone causes the greatest reduction in fat mass, it may be more important to point out that the results also show that a combination of cardio and resistance training is the most beneficial for improving overall body composition!
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