Choosing the right strategy to improve body composition is a hot topic, with many different exercise and dietary strategies suggested to be successful for weight loss, reducing body fat, and preserving lean muscle mass. It is important to select the right approach that fits your individual needs. It is particularly encouraging that many studies show success in improving body composition with as little as three, thirty-minute workouts per week, provided they are combined with a diet regimen that is calorically neutral or hypocaloric[i]. These small studies have not only looked at exercise type but have included a variety of individuals of different ages and stages of mobility and fitness to elicit the major differences to best understand the magnitude of the effect and if any supplements might be useful.

How important is diet to body composition?

Your diet provides the fuel that your body requires to make it through the day’s energy needs.  There is a lot of information out there and fad diets are constantly coming in and out of favour. Options such as ketogenic and Palaeolithic diets depend on unique macronutrient preferences such as higher fat or higher protein where approaches such as intermittent fasting focus more on when you are allowed to consume your calories. While these diets have become increasingly popular, when it comes to weight management and body composition – it is important to select options that work for you and your dietary preferences and lifestyle.   The research is favourable that, provided you are complying with a diet that is allowing for caloric control and you are motivated to exercise; you will see improvement to your body composition.  Simply put, it requires dedication and adherence – a caloric restriction of 500 kcal per day, from diet and exercise expenditure, will result in one pound of weight loss per week.

Isn’t there risk of muscle loss if you are not eating enough to feed those muscles?

What is clear is that if the goal is sustained fat loss, there must be a caloric deficit of some kind, whereas if the goal is to build lean mass it is best done through resistance training and caloric excess with proper attention to protein requirements[ii]. For those who are looking to reduce their body fat but want to maintain muscle mass, attention to protein intake is crucial. Increased protein intake of up to 2.3-3.1 g/kg bodyweight can benefit muscle retention in times of reduced caloric intake while undergoing resistance-based training[iii].  

Do I burn more fat if I exercise fasted?

This is a popular myth but it does not appear as though exercising in a fasted state will burn more fat compared to those who are well fuelled for exercise. Schoenfeld and his colleagues looked at a small group of healthy female volunteers divided into a fasted exercise group and a fuelled exercise group – both underwent hypocaloric dietary restriction and performed one hour of steady low-moderate aerobic exercise three times per week[iv]. While both groups experienced significant weight and fat mass loss after four weeks, there were no significant differences between the two groups. This implies that there is no benefit to exercising in a fasted state and that it may be more about your personal preference. If you prefer to exercise on an empty stomach or first thing in the morning before meals then, as long as it is effective and safe, this strategy can work for you. Others prefer better nutrient timing so that they feel at their best for each workout.

While the myth is incorrect, the benefits to intermittent fasting -only eating during a specific timing window and abstaining from food outside of that window, should not be discounted. Hayward et al demonstrated that an eight-hour eating window and 16-hour fasting period has shown reduction in fat mass and weight when combined with resistance training and caloric restriction[v]. Fasting patterns in animal models have been shown to improve the ageing process and protect against obesity, whereas human data demonstrates improvement to insulin sensitivity[vi].

Are there supplements that help improve body composition?

There are several supplements that show positive data helping improve body composition. EPA and DHA, constituents found in fish oil, have been shown to suppress genes that increase fat accumulation as well as increase transportation of fatty acids into the inner mitochondria for breakdown[vii]. This is important as there is still the active myth that eating fat will make you fat. Animal studies show that not all types of dietary fat have negative results. Rats fed a diet rich in omega 3s, show less total body fat and intra-abdominal fat as well as lower insulin resistance compared to those fed diets rich in other fatty acids such as lard and corn oil[viii].  Noreen et al. looked at the effects of fish oil on fat accumulation in healthy adults versus a safflower oil control group[ix]. After six weeks of taking 4 g of fish oil containing 1,600 mg EPA and 800 mg DHA improvements to lean mass and decreased fat mass was observed along with lowered cortisol. 

Another interesting study looked at the effect of resistance-based exercise, diet and supplementation of glucosamine, chondroitin and MSM on body composition in sedentary women between the ages of 46 and 63 with osteoarthritis of the knee[x]. In this study, participants were assigned to a neutral calorie high-carb/low-fat diet or high-protein diet and were assigned a 30-minute exercise program, three times per week, for 14 weeks. Not surprisingly, all dietary groups had reduction in body weight and fat mass.  While the glucosamine, chondroitin and MSM group had equal results to the placebo group, they did report improved perception of knee pain. This study is important as you are never too old to start exercising but proper attention to maintenance and ensuring you feel your best must always be considered.

Works Cited

[i] Magrans-Courtney, Teresa, et al. “Effects of diet type and supplementation of glucosamine, chondroitin and MSM on body composition , funcitonal status, and markers of health in women with knee osteoarthritis initiating a resistance-based exercise and weight loss program.” Journal of the International Society of Sports Nutrition 8, no. 8 (2011).

[ii] Aragon, Alan, et al. “International Society of Sports Nutrition Position Stand: diets and body composition.” Journal of the International Society of SPorts Nutrition 14, no. 16 (2017).

[iii] Antonio, Jose, et al. “A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women – a follow up investigation.” Journal of the International Society of Sports medicine 12 (2015): 1-9.

[iv] Schoenfeld, Brad Jon, Alan Albert Aragon, Colin D Wilborn, James W Krieger, and Gul T Sonmez. “Body composition changes associated with fasted versus non-fasted aerobic exercise.” Journal of the International Society of Sports Nutrition 11, no. 54 (2014).

[v] Hayward, Sara, et al. “Effects of intermittent fasting on markers of body composition and mood state.” Journal of the International Society of Sports Nutrition 11 (suppl 1), no. P25 (2014).

[vi] Freire, Rachel. “Scientific evidence of diets for weight loss: different macronutrient composition, intermittent fasting and popular diets.” Nutrition 69, no. 110549 (2020).

[vii] Noreen, Eric E, Michael J Sass, Megan L Crowe, Vanessa A Pabon, Josef Brandauer, and Lindsay K Averill. “Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults.” Journal of the International Society of Sports Nutrition, 2010: 1-7.

[viii] Hill, J O, J C Peters, D Lin, Yakubu F, H Greene, and L Swift. “Lipid accumulation and body fat distribution is influenced by type of dietary fat fed to rats.” International journal of obesity and related metabolic disorders: journal of the international association for the study of obesity 17, no. 4 (1993): 223-236.

[ix] Noreen, Eric E, Michael J Sass, Megan L Crowe, Vanessa A Pabon, Josef Brandauer, and Lindsay K Averill. “Effects of supplemental fish oil on resting metabolic rate, body composition, and salivary cortisol in healthy adults.” Journal of the International Society of Sports Nutrition, 2010: 1-7.

[x] Magrans-Courtney, Teresa, et al. “Effects of diet type and supplementation of glucosamine, chondroitin and MSM on body composition , funcitonal status, and markers of health in women with knee osteoarthritis initiating a resistance-based exercise and weight loss program.” Journal of the International Society of Sports Nutrition 8, no. 8 (2011).