There are two approaches to resistance training. You can lift heavy weights and do fewer repetitions or use lighter weights and increase the number of repetitions you do. Using heavy weights is preferable for building strength, as your strength gains will be limited if you don’t work with a challenging resistance. Without intensity, you don’t maximize the activation of your fast-twitch muscle fibers.
Lighter weights and higher reps is an approach that works well if you’re trying to build muscle endurance, the ability of a muscle to sustain repeated contractions without fatiguing. Building muscle endurance can help your muscles sustain contractions for longer periods without tiring. This comes in handy if you’re a long-distance runner, a cycler, or a rower.
What’s the Best Rep Range for Fat Loss?
You might be interested in building strength but what’s the most effective approach if your goal is fat loss? Some sources say lighter weights are better for fat loss, as you do repetitions, and more movement leads to greater calorie burn. But the calories you burn during a training session are only one aspect of fat loss. Lifting lighter weights and doing more repetitions doesn’t challenge your body as much or force it to work as hard as working with heavier weights.
Why is intensity important? When you struggle to lift a heavy weight, it places more stress on your body and you produce hormones like epinephrine and norepinephrine that boost your heart rate and increase blood flow to your hard-working muscles. These hormones also rev up your metabolism. Some studies also show that lifting heavy enhances the release of testosterone and growth hormone, an anabolic hormone that helps with fat loss.
Plus, your body recovers slower from an intense resistance training session that involves heavy weights. During the recovery period, your body has higher oxygen requirements and uses more calories for activities, such as restoring a healthy pH (acid-base balance). It also ramps up the calorie burn to lower body temperature, remove lactic acid, replenish muscle glycogen, and slow your breathing rate.
Working with heavy weights is a bigger disruptor to homeostasis, so the increased oxygen utilization and calorie burn are higher in the 24 hours after such a workout. This phenomenon known as the afterburn effect doesn’t occur to the same degree with low to moderate-intensity exercise.
All these things work in your favor if you’re trying to shed extra pounds of body fat.
Working with Heavy Weights Offers a Growth Hormone Advantage
A study published in the American Journal of Physiology-Endocrinology and Metabolism looked at the effects of different resistance training approaches on growth hormone in women. The study found that women who used varying degrees of weight loading, including some heavier weights, optimized growth hormone release. So, it may not be “either-or” but both approaches, light weights, and heavy weights, that maximize fat loss.
There are reasons you should include heavy sets in your weight-training routine. Working with heavy weights maximizes strength gains and stimulates the laydown of new bone. Lifting lighter weights has less impact on bone health. Some women hesitate to lift heavy because they fear getting bulky. Research shows that’s not likely; it’s more probable that they’ll get leaner and stronger.
Emphasize Compound Exercises for Fat Loss
Whether you lift mostly light or heavy, there are tweaks you can make to your routine to optimize fat loss. The more muscles you work during an exercise, the more calories you’ll burn. That’s why compound, or multi-joint, exercises, like squats, deadlifts, push-ups, pull-ups, lunges, and bench press, will give you more return than exercises, like biceps curls and leg extensions, which work a single muscle group in isolation.
If you’re trying to lose body fat, 3 out of 4 resistance exercises should be multi-joint or compound movements. Start with compound exercises and save isolation exercises for later in your workout, so you can maximize your performance on multi-joint exercises.
You Need Resistance Training for Maximal Fat Loss
Regardless of your repetition scheme, working your muscles against resistance is important for body composition. When you restrict calories to lose weight, you lose body fat and muscle. Resistance training helps preserve and even build muscle while you’re cutting back on calories to lose weight. You don’t want to lose muscle, only excess body fat.
Don’t assume aerobic exercise that elevates your heart rate for prolonged periods of time is the only or best option for fat loss. Studies show a combination of aerobic exercise and weight training leads to greater weight loss than cardio alone. Cardio burns more calories while you’re doing it, but your metabolism stays higher longer after weight training.
Make sure you’re doing both resistance training and cardio to maximize fat loss and ensure you’re including some exercises that use heavy resistance to boost growth hormone release and the afterburn effect. Both can help with fat loss.
The Bottom Line
Include both high resistance, low reps, and low resistance, high rep training in your program for fat loss. High resistance training will give you the greatest fat loss benefits, but you should also vary the stimulus you place on your muscles. Lighter weights and higher reps give your muscles and nervous system a break.
References:
- Geliebter A, Maher MM, Gerace L, Gutin B, Heymsfield SB, Hashim SA. Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects. Am J Clin Nutr. 1997 Sep;66(3):557-63. doi: 10.1093/ajcn/66.3.557. PMID: 9280173.
- Craig BW, Brown R, Everhart J. Effects of progressive resistance training on growth hormone and testosterone levels in young and elderly subjects. Mech Ageing Dev. 1989 Aug;49(2):159-69. doi: 10.1016/0047-6374(89)90099-7. PMID: 2796409.
- “Varying Weight Training Intensity Increases Growth Hormone ….” 04 Dec. 2006, sciencedaily.com/releases/2006/12/061201105951.htm.
- Wilk M, Petr M, Krzysztofik M, Zajac A, Stastny P. Endocrine response to high intensity barbell squats performed with constant movement tempo and variable training volume. Neuro Endocrinol Lett. 2018 Oct;39(4):342-348. PMID: 30531700.
- American Physiological Society. “Varying Weight Training Intensity Increases Growth Hormone in Women.” ScienceDaily. ScienceDaily, 4 December 2006. <www.sciencedaily.com/releases/2006/12/061201105951.htm>.
- “The BEST Resistance-training Program for Fat Loss.” 05 Dec. 2017, acefitness.org/education-and-resources/professional/expert-articles/6868/the-best-resistance-training-program-for-fat-loss/.
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Weight Training: Low Reps or High Reps for Weight Loss?
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What Does Research Show about Partial Reps vs. Full Reps for Strength Training?
Why We Use Compound and Combo Exercises in the Low Impact Series
What Types of Exercise Cause an Afterburn?
Rep Speed: Are Fast or Slow Reps Better for Building Strength?
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STS Strength 90 Day Workout Program
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