How should I lift weights while dieting? Everyone at the gym and all the magazines say to go high rep to burn the fat. Does high rep training really burn fat better? Is this the best approach to training while dieting?
While high rep, short rest interval training does have the potential to burn a fair number of calories, training during a fat loss stage should be used to preserve (or even increase) muscle mass as opposed to stimulating fat loss. Fat loss is going to, or should, come primarily from nutrition, with the rest coming from various forms of cardiovascular work (HIIT, interval training, some steady state cardio, etc.) Your weight training should be focused primarily on getting strong, and keeping the muscle you have, not fat loss. Let the other 23 hours of the day take care of the fat loss.
Your best bet is to avoid a lot of high-rep, low-load training while dieting. Your body already has a limited capacity to recover due to a lack of fuel/substrate when on reduced calories. Light weights while in caloric deficit will likely result in more muscle loss, as your body, while attempting to adapt to a caloric deficit will try to ‘slow down’ over time. This happens via various hormonal responses as well as by eliminating the more metabolically active tissue – muscle. Your body will always attempt to adapt to any change you throw at it – and this includes a caloric deficit. The more you deviate from your ‘set point’, the more your body will respond to bring you back.
Hormones respond to over and undereating. On reduced calories and as your bodyfat drops, catabolic hormones rise, promoting increased amino acid oxidation (protein breakdown) and anabolic hormones fall. Net protein accretion/retention decreases, protein oxidation increases, cell volume generally decreases, leptin production decreases, etc., etc. Remember, what builds muscle is what keeps muscle, and if you don’t use it, you’ll lose it. You need to give your body a reason to hold onto the muscle and this requires you to be training above a minimum intensity threshold. So, quite simply don’t bother with these 15-20 rep sets. Train heavy and try to get and/or stay strong.
The other thing to consider when comparing heavy versus light training while dieting is the effect each has on the look, or quality, of the muscles. Training with heavy weights improves both myogenic and neurogenic tone. The first refers to your muscle tone at rest while the second refers to muscle tone that is expressed when movements occur. Neurogenic tone is improved due to the effect lower rep training has on the sensitivity of various motor neurons. Myogenic tone is affected by the density of your muscles and is improved by stimulation of the contractile proteins, again via heavy low, low rep training. Higher rep ranges unfortunately do not offer these benefits, and let’s be honest, high rep training just isn’t fun anyway. When a body is stripped of much of its fat, muscle density and hardness go a long way to enhancing the quality of a person’s physique. Excluding the heavy, low rep work in favour of the oft prescribed high rep, short rest interval work for fat loss training will not have nearly the same effect that focusing your training on heavy loads will have.
The last thing to keep in mind and this was touched on earlier, is that your capacity to recover from training is decreased on reduced calories. As a result, the volume of your training (sets x reps) needs to be reduced. Always keep in mind the goals of resistance training while dieting – maintenance of strength and muscle size. You’re simply not going to be making significant muscular gains while in a caloric deficit – no matter what anyone tells you. If you try to keep the volume as high as you might have it when your calories are above maintenance, you’re going to find yourself burning out, getting weaker, and regressing. You can decrease volume by as much as 2/3 when dieting. I’d typically err on the side of caution and do less when you want to do more.
Remember what builds muscle, is what keeps muscle.