Shredding: How to retain muscle, whilst losing weight – A scientific look
More and more people nowadays want to get ‘shredded’ – a chiseled body that has zero fat and is pure muscle.
There are a lot of ways to get naturally shredded but the most influential factors come down to diet and physical activity. Below I discuss the essential components, with some support from scientific literature, on the effects that various diets and levels of exercise have on losing fat whilst retaining muscle. For the purposes of simplicity, I have excluded discussing supplements and drugs in this post. Let’s begin!
So you want to lose weight, great! The problem, however, is that when one loses weight, they lose BOTH fat and lean body mass (Dulloo, Jacquet & Girardier, 1996). For a person of normal weight who eats a calorically restricted diet, as much as 35% of the total decrease in body weight is from the loss of muscle tissue (Bosy-Westphal et al., 2009). This is more likely to occur in men, who typically lose more lean body mass than women due to the fact that men are generally leaner overall (Sartorio, Maffiuletti, Agosti & Lafortuna, 2005).
On a technical level, when losing weight, our body continues to synthesize protein unabated. The reduction of lean body mass that we see is due to the body breaking down existing muscle (a process known as proteolysis) (Edda, Nai & Bettina, 2016). To attenuate this process, we have to look at our diet and training.
Unsurprisingly, when it comes to weight loss, diet is an essential factor. Generally speaking, you’ll want to do two things with your diet:
A high protein diet is where the amount of protein consumed is above the recommended daily allowance (RDA) of 0.8g per kg of lean body weight. How much above the RDA is widely debated amongst scientific literature. A study by Mettler, Mitchell & Tipton (2010) performed on 20 resistance trained athletes, found that around 2.3g of protein per kg of lean body weight, resulted in statistically less muscle loss than those athletes consuming 1.0g per kg of lean body weight.
This recommendation, however, needs to be considered in light of parallel studies conducted on the detriments of consuming a high protein diet above the RDA level. “Extra protein is not used efficiently by the body and may impose a metabolic burden on the bones, kidneys and liver” (Ioannis, 2013).
Personally, I consume 1.7g to 2g per kg of lean body weight and since my lean mass is around 65kg, my protein hovers around 130g per day.
The premise behind a high protein diet is that, consuming a higher than normal level of protein results in the higher availability of amino acids in the body and causes higher protein synthesis (muscle building).
Several studies were conducted on the changes in the body composition of individuals who did not consume an elevated level of protein whilst on a calorically reduced diet, but instead consumed only the RDA level of protein (0.8g per kg). Participants on a Very Low-Calorie Diet (400 – 800 calories per day) saw rapid weight loss, but 25% of this weight loss was a result of decreased muscle mass (Hoie, Bruusgaard & Thom, 1993).
In terms of timing your protein intake, it is better to take a protein supplement within 2 hours of your resistance training. A study was conducted on elderly men who performed a leg based resistance training regime followed by the intake of protein. Results showed that the participants’ quadricep muscles had a larger cross-sectional area when compared with those who did not follow their exercise with protein (Esmarch et al. (2001)).
For the remainder of your protein, it is advised to distribute it evenly throughout the day. This was supported by 2 studies conducted on healthy young and middle aged men who reported a greater overall daily muscle protein synthesis rate when protein was consumed evenly throughout the day (Farsijani et al., 2016).
Calories are essential to control when you want to lose weight because it is the net deficit in calories that causes weight loss. A caloric deficit is when you eat less or burn off more calories than your body needs to maintain its current body weight, resulting in body fat being utilised for energy. The more you can restrict the intake of calories, the more you can increase the size of this deficit and thus the faster the weight loss will occur.
There are many diets out there that promote weight loss (such as the ketogenic diet, Atkins diet or the high fiber diet) but the common factor amongst all of these is that they all restrict calories in one shape or another.
As already described above, you’ll want to consume a high protein diet, but this increase in protein should not result in an increase in the total amount of calories you have restricted yourself to for the day. You’ll still need to stay within your restricted calorie limits.
The amount of calories you should consume varies from person to person and there are many factors that influence the amount (from age, height, lean body mass weight, rate of desired weight loss etc.). A qualified dietician can develop an appropriate eating plan for you, but you can get rough estimates from online calorie calculators (there are many on bodybuilding.com).
Calorie Decrease Timing
The current belief in the fitness community is that when wanting to maximise fat loss but minimise muscle loss, you’ll want to gradually reduce the calories you intake over a period of time. Reducing your calories too harshly increases the risk that your body will digest more muscle than necessary as it burns off fat. So essentially if your base calorie level per day is 3,000 kcal, you can gradually reduce this amount by 200 kcal per week as an example.
As mentioned above, the pace at which you reduce your calories is individualistic, but as a general guideline, aim to lose at most 2 lbs (or 0.9kg) per week.
When in a caloric deficit, continued resistance training is widely agreed to be a necessity to reduce the loss of muscle mass.
This is because resistance training both promotes protein synthesis and enhances the inhibitory effect insulin has on the breakdown of the muscle. A study was conducted on middle-aged to older men and women in which they were served a low calorie diet. Half the group combined the diet with around 300 minutes of walking per week, whilst the other half did no exercise. It was found that the group that continued to exercise, lost only half as much thigh muscle as the no exercise group (Yoshimura et al., 2014).
When wanting to lose weight but retain muscle, make sure that you follow the below guidelines:
Yoshimura E.; Kumahara H.; Tobina T.; Matsuda T.; Watabe K.; Matono S.; Ayabe M.; Kiyonaga A.; Anzai K.; Higaki Y. et al. Aerobic exercise attenuates the loss of skeletal muscle during energy restriction in adults with visceral adiposity. Obes Facts 2014