The cardio vs. weight lifting for weight loss debate stems from the days when “cardio” usually meant going for a jog and “weightlifting” meant pumping iron in a sweaty gym. If those are the only two options you’ll consider for your weight-loss routine, then go with weightlifting.
Weightlifting will win the weight-loss war every time because it builds more “metabolically active” tissue (AKA muscle), raising the number of calories you must burn each day just to stay alive and kicking. It also causes more “micro trauma” to muscles, requiring a more intensive recovery process that raises your metabolism for up to 72 hours post workout. In short, any way you look at it, weightlifting will cause you to burn more calories, overall.
But there’s a third, even more effective option: high intensity interval training (HIIT), which combines cardio and strength training (notice we didn’t say “weightlifting”— you don’t need to lift weights to build strength) in the same workout to maximize calorie burn both during exercise and in the hours and days afterward.
Exercise, however, is just one element of a successful weight-loss plan. To lose weight and to make it stick, you have to adjust your entire lifestyle, including your diet and sleeping habits. Why? Because all of these things affect your body’s ability to change.
A Quick Primer on How Sleep and Dietary Habits Affect Weight Loss
When you skimp on sleep, your hormones go haywire, which can cause you to pack on extra pounds. A study published in the Journal of Thoracic Disease revealed that poor sleep can contribute to weight gain because it may cause shifts in cortisol levels, appetite, and hormones such as ghrelin, which research suggests can play a role in meal initiation. Not getting enough quality sleep can decrease basal metabolic rate by up to 30 percent, and may also impact workout performance, mood, and mental health, the study reported.
No matter how well-rested you might be, though, you will not lose weight if you don’t create a caloric deficit, which starts with making adjustments to your diet. To do this in a way that optimizes overall health and (hopefully) won’t make you miserable, make sure you:
Now that you’re better informed about what changes you might need to make to your dietary and sleep regimens, it’s time to focus on the other half of the weight-loss equation: exercise.
How HIIT Can Accelerate Fat Loss
The key to losing weight is changing your metabolism. While it’s easier to alter your metabolism through strength training than cardio, both will do it if the workouts are well designed. But they’ll do it even better if you combine them.
The most important variable when it comes to losing weight through exercise is workout intensity. By that, we mean that you need to force your body to work in the anaerobic realm, in which your muscles’ demand for energy exceeds your ability to produce it aerobically (i.e., with oxygen).
In practice, that entails exercising at 84 percent or more of your maximum effort for up to two minutes at a time. If you’re thinking that sounds like high intensity interval training (HIIT), you’re right. That’s what we mean by “combining” strength and cardio. And the reasons that such anaerobic training trumps traditional cardio (think: steady state running or biking) for weight loss is not because of how many calories you burn during exercise (traditional cardio still wins there… maybe), but because of how many calories you burn afterward.
Anaerobic training primarily targets type II (fast twitch) muscle fibers, which are larger and have more growth potential than the type I (slow twitch) fibers targeted by aerobic training. It also causes more damage on the cellular level. Those two facts are important for weight loss for two reasons: Anaerobic training builds more metabolically active tissue (i.e., muscle), causing a permanent increase in your daily caloric burn, and the repair process is more extensive, causing an acute increase in your metabolism for up to 72 hours after you work out.
But just as important as the amount of weight lost is the kind of weight you lose. Research shows that for a given amount of lost weight, anaerobic training causes more of it to come from fat. Indeed, a study at the University of Connecticut found that 12 weeks of a low-calorie diet combined with either aerobic exercise or a mix of aerobic and anaerobic exercise resulted in about 21 pounds of weight loss. But the participants in the anaerobically-trained group lost only fat, while those who performed only aerobic training lost up to five pounds of muscle.
The results of that study might also seem to support two of the most enduring myths regarding strength raining and cardio — namely, that the latter can make you bulky and the former doesn’t build muscle. So let’s dispel these untruths once and for all.
Workout for Weight Loss Myth: Strength Training Makes You Bulky
Gaining bulk is hard. That fact is why bodybuilders and hardcore gym rats cringe when they hear people (especially women) say, “Strength training will make me bulky.”
It takes a ton of energy for your body to add muscle. During the initial stages of any kind of intense training program, especially one that you’re not used to, your body releases excess amounts of the hormone cortisol, which causes your body to retain water. Some people think this means they are bulking up when, in reality, it’s just their bodies adapting to the training. It has nothing to do with gaining actual muscle mass. Once your body adapts to the new training, the cortisol release ceases and your body flushes the excess water.
Even after that initial adjustment period, it would take months or even years of heavy weightlifting for a man to build the kind of body that most people consider “bulky.” For most women, it’s not even a possibility (you can blame or thank genetics). Regardless, if you stick to HIIT, what you’ll more likely notice in the mirror (regardless of gender) is a leaner, stronger, more defined physique.
Workout for Weight Loss Myth: Cardio Doesn’t Build Muscle
This second myth is trickier. Low-intensity, steady-state aerobic training isn’t an efficient way to build the kind of metabolically active tissue (i.e. muscle) that optimizes weight loss. But that’s not the only way to do “cardio,” which has become a catchall term for any training that elevates your heart rate for the entire workout. These days, since almost all weight training is done circuit-style, your heart rate remains elevated during both cardio and weight training workouts. Modern cardio training is almost always an offshoot of interval training, which means it’s a mix of aerobic and anaerobic training. And that builds muscle.
Adding muscle increases your metabolism and that’s what helps you lose weight… as long as you’re not eating too much.
The Final Piece of the Weight-Loss Puzzle: Recovery
Recovering adequately between workouts is critical for losing weight. That’s why having a system is so important. Intense anaerobic training is stressful for your body. You need this stress to change your hormone balance. But if you overstress your body, it will lead to problems in the form of overreaching. If this goes on for too long, overtraining will occur. Both overreaching and overtraining can cause setbacks ranging from chronic fatigue and soreness to injury and illness. A proper exercise program prevents that from happening by alternating between different workout styles and intensities (e.g. HIIT and yoga) to create a balance between intense exercise and recovery.
Nutrition is also very important for proper recovery. The better you eat, the faster you recover. Ditto for sleep. Sleep is when your body elevates its production of its natural PEDs (performance-enhancing drugs — in this case, testosterone and growth hormone). So get your shuteye!
The 10-Second Takeaway
To recap, the important factors for weight loss are: pushing yourself beyond your comfort zone in your workouts (i.e., doing high intensity exercise), eating enough to recover (but not more than that), and getting adequate rest. Balance these factors (exercise, diet, and recovery) correctly, and your metabolism will shift and the pounds will melt away.