A calorie deficit is where you eat under your maintence calories which creates a negative energy balance meaning you are using more energy than you are fueling the body with. A calorie deficit is beneficial if you are wanting to improve body composition as it will allow for you to decrease your body fat. There are lots of different diets that are in circulation to help people improve body composition and enter a calorie deficit. Lots of research has looked into the success of these diets to see if there are some diets better than others. The research has suggested that there is no superior diet due to the fact that they all create a calorie deficit, which is what is required to lose body fat. This is why it is important that food groups should not be looked at as being ‘bad’ foods and ‘good’ foods. No matter what foods you eat you can always create a calorie deficit there are just more favourable food groups that are recommended. (Sherman, 2020)
Lean body mass in a calorie deficit
When in a calorie deficit lean body mass is important to keep as high as it can be, while the fat mass drops. But due to a negative energy balance it can mean it can start to decrease along side the fat mass so it’s important your nutrition is where it needs to be to minimise it. Research suggest that a higher protein intake while in a calorie deficit (approximately 2g/kg body weight/day if not more) is needed to help preserve your lean body mass. Along side this it has also been discovered that exercising within a calorie deficit helps to also minimise the loss of lean body mass. So when trying to improve body composition it is important to keep protein high and continue to exercise to help minimise the decrease of lean body mass, while your fat mass is dropping. (Weiss, et al., 2017, Willoughby, et al., 2018)
Calorie deficit and performance
Eating in a calorie deficit as already stated creates a negative energy balance which can mean performing optimally can be difficult. Across 6 different studies that looked at the impact of a negative energy balance on a performance, within 3 of them there was no association between decreased performance and a calorie deficit. However within the other 3 both anaerobic and aerobic performance decreased. However this was observed across 2 groups of people. Group 1 was slow rates of weigh tloss (0.7% reduction of body mass over a 30 day period), Group 2 was a fast rate of weight loss (1.4% reduction of body mass over a 30 day period). Group 1’s performance was not impacted as much as Group 2’s meaning that being in a smaller calorie deficit is more beneficial as it will still allow you to perform well while improving your body composition. (Thomas, et al., 2016)
