Which Workout is Best for Weight Loss?

Everyone understands that exercise is essential for a healthy life and keeping fit. But not all types of exercise are created equal. Many people overlook the importance of diversifying the types of training they engage in, especially when weight loss is the primary goal. 

After all, working out is what turns kicks your metabolism into top gear to facilitate the fat-burning process — assuming you're doing the right exercises. So, what is the best workout to lose weight? Should you lift weights to burn body fat or focus more on cardio? 

Let's take a look at how to exercise for weight loss and why there's more to the equation than just the amount of calories you burn during your workouts. 

Aerobic vs. Anaerobic Exercise for Weight Loss

While a proper diet is crucial if you're trying to lose weight, it will never replace the necessity of a diligent workout regimen. At its simplest, exercise is a means of burning calories (energy). Even a walk around the neighborhood classifies as exercise. 

However, to truly capitalize on the metabolic benefits of physical activity, you need to turn the intensity up a few notches. Low-intensity exercises like walking and leisurely riding the bike rely predominately on aerobic respiration for energy. In short, aerobic exercise is easier to sustain for long durations since the intensity isn't high enough to deprive muscle tissue of oxygen.  

That's just one reason why you can maintain a steady pace when jogging a mile. But what happens if you try to sprint a mile? Well, you probably can't. If you're running as fast as you possibly can, your circulatory system can't deliver oxygen rapidly enough to muscle tissue to keep up with the exercise. Hence, high-intensity workouts rely on anaerobic respiration for energy. 

The primary substrates used to create adenosine triphosphate (ATP) during high-intensity exercise are phosphocreatine and glucose, and a waste product of anaerobic glycolysis (sugar metabolism) is lactate. As lactate accumulates in your muscle tissue during a heavy set of barbell squats, for example, intramuscular pH drops (read: becomes more acidic) and leads to that familiar "burning" sensation. 

Thus, anaerobic metabolism is limited in capacity since it's less efficient than aerobic metabolism, which does not produce a significant amount of lactate. Aerobic metabolism primarily oxidizes ("burns") glucose and fatty acids for energy, with the final waste products being water and carbon dioxide (both of which are readily exhaled).

High-Intensity vs. Low-Intensity Exercise

The physiological benefits of aerobic and anaerobic exercise are quite distinct. Walking at a brisk pace, for example, is mostly just a way to burn calories.

On the flip side, the metabolic benefits of high-intensity training, like 100-meter sprint intervals, are myriad. You may not burn as many calories during your workout, but the "afterburn" effect more than compensates for that. 

In other words, intense anaerobic exercise conditions your body to burn more energy in the 22-23 hours of the day that you're not exercising. Low-intensity aerobic exercise does not do that. 

Frequent, lengthy bouts of low-intensity cardio are not the solution for lasting results. In reality, you want to keep cardio as minimal as possible even when your goal is to lose weight. 

Now, that's not to say that low-intensity exercise is inherently worthless. Going for a walk after a long day at the office is undoubtedly beneficial, especially if you have physical limitations that prevent you from exercising vigorously. 

However, the perpetual metabolic effects of intense training make it the prudent option for sustainable weight loss. Besides, who wants to mindlessly stride away on the elliptical every day to lose weight? Those hours of soul-sucking cardio will be a thing of the past once you pick up the intensity a bit. 

With that in mind, let's briefly look at the science of training intensity and how it governs physiological responses to exercise.

High-Intensity Exercise: Benefits Beyond Exertion

In scientific literature, "high-intensity exercise training (HIET)" refers to exercise performed at or above the lactate/lactic acid threshold [1]. (The term HIET is synonymous with high-intensity interval training (HIIT). Therefore, HIET/HIIT is limited by anaerobic metabolism since it creates lactate as a waste product. Recall that lactate is that pesky molecule responsible for the "burning" sensation you feel in your muscles after vigorously exerting yourself for as long as possible. 

Contrast that with low-intensity exercise (e.g. walking), which you may be able to sustain for hours on end with little-to-no perceivable "burning" in your legs. Aerobic exercise isn't intense enough to reach the lactic acid threshold. 

What that tells us is pushing ourselves to the "limit" where the burning sensation becomes palpable is when the benefits of intense exercise start to kick in. Yes, it's strenuous and uncomfortable, but hey — no pain, no gain, right? 

Here are a few reasons why high-intensity exercise is best for weight loss (and building muscle):

Intense Exercise Stimulates Mitochondrial Biogenesis (and Boosts Metabolic Rate)

Mitochondria are the veritable "powerhouses" of cells. They are essentially where your cells generate the most energy (ATP). Mitochondria are key regulators of metabolic rate since they contain a family of uncoupling proteins (UCPs) that modulate thermogenesis. Hence, the more mitochondria you have, the greater your energy output (i.e. calorie expenditure). 

Research has shown that skeletal muscles undergo mitochondrial biogenesis — the process by which cells create new mitochondria — after high-intensity exercise (but not low-intensity exercise) [2]. Moreover, UCP expression increases dramatically in skeletal muscle tissue - upwards of 8-fold - shortly after vigorous exercise (and remains elevated 24 hours after that) [3]. 

In laymen's terms, training vigorously for as few as 20-30 minutes will elevate your basal metabolic rate (BMR) for many hours afterward. Jogging for an hour (or longer) will not lead to that same "afterburn" effect.

Vigorous Exercise Reduces Waist Circumference and Visceral Fat Tissue 

Visceral fat tissue is the fat that surrounds internal organs and lies beneath subcutaneous fat (think: "beer belly" or "stubborn body fat"). Aside from the aesthetic ramifications of carrying excess visceral fat, it's quite harmful for your health and longevity.

The good news is that research has found a significant inverse correlation between visceral fat tissue and serum growth hormone levels in subjects that train to the anaerobic/lactate threshold [4]. Furthermore, the anaerobic threshold group had significant increases in BMR and reductions in waist circumference compared to subjects that completed low-intensity exercise or no exercise.

More simply, vigorous exercise reduces visceral fat tissue and slims the waistline better than low-intensity exercise.

Train Hard to Increase Growth Hormone and Testosterone

Shortly after a bout of high-intensity exercise, the body produces a burst of growth hormone, a potent fat-burning hormone that increases fatty acid oxidation [5]. Testosterone also increases after vigorous exercise and remains elevated as long as intense training remains consistent [6]. Testosterone is one of the most potent anabolic hormones in humans. 

Intuitively, the more testosterone and growth hormone your body produces, the easier it is to lose fat and build muscle. Now, don't misconstrue that as saying you will turn into a shredded bodybuilder just because you do some high-intensity interval training. The key takeaway here is that vigorous exercise encourages endocrine responses conducive to weight loss and muscle preservation. 

Transparent Labs Vitality features clinically studied ingredients that can further support natural testosterone levels and improve your testosterone-to-cortisol ratio. 

Anaerobic Exercise Improves Insulin Sensitivity

Insulin resistance refers to the phenomenon of cells becoming unresponsive to insulin signaling. In other words, insulin no longer triggers the usual blood-glucose-lowering effect when binding to its receptor. 

Contrarily, being highly "insulin-sensitive" means your body handles and partitions carbohydrates more favorably. Vigorous anaerobic exercise has been shown to significantly improve insulin sensitivity in healthy adults and people with type-2 diabetes [7, 8]. 

Remember, anaerobic exercise is primarily glycolytic. The more sensitive your body is to insulin, the better it becomes at utilizing glucose for energy during an intense workout. This is advantageous for preserving muscle tissue on a weight-loss diet since glucose is a protein-sparing nutrient. 

Essentially, training intensely allows you to eat more carbs while simultaneously losing weight and retaining more lean body mass. 

Take-Home Points

High-intensity forms of exercise, especially resistance training, should be your priority for improving body composition and getting lean. Training at higher intensities is unequivocally superior for long-term, sustainable weight loss since it keeps your metabolism firing on all cylinders. 

It's quite common for women to fear that lifting weights will make them "bulky," which is just nonsense. Nobody, regardless of biological sex, has ever "unwittingly" gotten jacked. Not to mention, you won't be building much muscle mass when you're in a calorie deficit. 

Rather than slaving away on the treadmill for hours every time you hit the gym, you're better off doing a brief session of all-out sprint intervals on the bike or pumping some iron. As they say, go hard or go home. (Or, in this case, go hard, then go home.) 

Of course, there's one thing that tends to scare people away from high-intensity exercise: it burns! 

Just keep in mind that the payoff is well worth it. Maybe there is some inherent verity to the adage, "No pain, no gain," after all?