Resistance training, also commonly called 'weight training', 'strength training', 'working out' or 'pumping iron' has a considerable effect on fat loss. The real word effect is a hotly debated topic. This form of exercise has been practiced all the way back to the ancient Greeks and Egyptians. There are many different varieties of resistance training:
Free Weights (Barbells and Dumbells)
Body Weight training (Yoga, calisthenics)
Resistance band workouts
Selectorized machines
Cables and cam based machines
Kettlebells
Medicine balls and sandbags
Suspension equipment (TRX and Rings)
Hydraulics and water resistance
Resistance training works by applying various forces to the body which induces muscular contractions. It is based on the principle of supercompensation where the muscles of the body will work to overcome a resistance force. Over the next few days, the muscle will repair and become stronger and/or bigger. Basically, you move something heavy and your muscles adapt so the next time you need to move a heavy object it will be easier. I think resistance training should be part of everyone's fitness programs. Yes, yes I know if you have a hammer everything looks like a nail and as a fitness trainer, of course, I would say something like this. However, objective data show it plays a large part in counteracting age-related muscle loss, building functional strength, and reducing body fat.
The main variables that predict calorie burn (energy consumption) during a weight lifting session are aerobic capacity, height, weight, body composition, age, sex, and total exercise volume. In other words, we all have individualized physiques that burn calories at different rates. You are special.
Unlike cardio training (biking, running, dancing, underwater basket weaving, etc.) resistance training preserves lean muscle mass while simultaneously reducing stores of body fat. Some research shows cardio training is superior to weight training for overall weight loss. Nonetheless, weight training seems to consistently outperform cardio training in the realm of fat loss. Lifting weights ensures the preservation (and sometimes the accumulation) of muscle mass. Lean muscle needs constant stimulus and an abundant amount of energy in order for the body to sustain itself. The human body wants to be as judicious as possible and will attempt to rid itself of any inefficiency. It takes a lot of energy to hold onto muscle. Therefore when doing copious amounts of cardio the body will burn fat and may actually reduce muscle tissue. When glucose and fat stores are depleted, your body will utilize muscle and break it down into individual amino acids for energy. How often do you see muscular marathon runners? If the body does not need extra muscle and carrying it decreases efficiency, it will slowly deplete the extra mass.
Cardio training of similar duration and intensity tends to burn more relative energy (calories) than weight training however resistance training may burn more absolute energy over the course of the day. Plus most weight training programs preserve lean muscle mass. If you only did cardio (and ate well) you would lose weight but your body shape would not change much. Whereas if you lift weights and eat well you'll change your shape and lose fat.
Now let's discuss EPOC. It is basically the afterburn effect of exercise. It stands for Excess Post-Exercise Oxygen Consumption. This is a crucially important process in potentiating body fat loss. It describes how long oxygen uptake remains elevated after an exercise bout in order to help the muscles recover. It is essentially the calories you burn after you finish exercising. It may be no surprise, but after a session of resistance, training EPOC remains elevated much longer (12--36 hours post-exercise) than if one only performed cardio (2 hours post-training). This afterburn effect is governed by length, type, intensity of exercise, fitness level, and diet. Data show High-intensity intervals may be a superior way to enhance EPOC when compared to long slow distance training. On the whole, however, it is difficult to say one form of cardio is better than another. Don't overthink it, just do it. An extensive review of the research literature on EPOC, Bersheim and Bahr (2003) concluded that:
“studies in which similar estimated energy cost or similar exercising VO2 have been used to equate continuous aerobic exercise and intermittent resistance exercise, have indicated that resistance exercise produces a greater EPOC response.”
Resistance training seems to produce a larger EPOC effect than continuous aerobics. Again the data is relative and highly individualized.
NOTE: EPOC accounts for some extra calorie burn but NOT hundreds of additional calories burned. Sorry, it probably doesn't count for all that much.
Resistance training increases the resting metabolic rate (RMR). This is the amount of energy (calories) one uses while at rest. Resting metabolic rate accounts for 60–75% of total energy expenditure per day in sedentary people. It is a major determinant of calorie burn and changes in body weight. Increasing lean muscle tissue through weight training will increase RMR. This is a highly individualized process and is different for everyone. Comparatively, aerobic workouts don't seem to elicit the same response in increased metabolism. Although, in exercise science circles there is a rabid debate on how much and for how long. Exciting stuff! The research on RMR and exercise is inconclusive, so it is hard to hang your hat on this one too.
Weight loss, particularly, fat loss (which is different than weight loss) is a multifaceted phenomenon in the human body caused by several factors. Let me be clear, cardio is great for a whole host of things (even weight loss) – it’s just not an efficient way to decrease body fat. Cardio makes humans hungry by directly affecting hunger hormones (grhelin and insulin) and if done enough, it will decrease the muscle-building hormone testosterone. Furthermore, many people feel it is a license to eat more. In the hierarchy of fat loss cardio ranks at the bottom:
Good genetics (blame or thank your parents)
Clean eating
Lots of non-exercise movement
Weight training
Cardio
At the end of the day, diet is the most important factor in weight loss. Tons of data show individuals with the most successful long term weight loss did it with diet and exercise. It is a Sissafian feat to attempt to lose weight and keep it off without focusing on both aspects. The best diet and exercise is the one you are consistently willing to do. That being said research suggests the principal way to achieve optimal results is with a combination of aerobic exercise, weight training, and diet. For instance, here is a sample workout program:
Monday: Full body resistance training workout followed by 8 min of HIIT
Wed: 20-40 min of steady-state cardio
Thurs: Full body resistance training workout followed by 8 min of HIIT
Fri: 20-40 min cardio
Weekend: Lots of walking and other non-exercise activity (NEAT)
Weight loss is not easy and neither is resistance training. Sugarcoating is for donuts. If it were easy nobody would be overweight. However, if you put in the work and are patient results will come!