Understanding the crucial relationship between caloric intake and weight loss is essential for anyone embarking on a journey to shed excess kilos. Although it is true that in order to lose body fat, we must take in less calories that we consume, it is arguably as important that those calories are not dropped by much more than 15% of you total caloric intake. This relatively modest decrease will not only minimise any drop in your metabolic rate but will also allow you to retain your hard-earned muscle and avoid RED-S which this blog will delve into.



Will a larger caloric intake drop result in faster weight loss?


The short answer is no. The main problem with drastically restricting your calorie intake is that you cause your metabolic rate to slow down. Your body will begin to hold on to fat and calories rather than burning them for energy meaning that this ‘starvation adaption response’ makes it harder for your body to burn fat.

Drastically cutting your calorie intake will also result in your glycogen stores to quickly deplete, causing a drop in performance, low energy levels and in turn less voluntary movement. You may even end up breaking down muscle tissue as well as fat to produce fuel in the body meaning you may lose your hard-earned muscle.



But I thought workouts on an empty stomach burned more fat?


There is a slight potential that exercising on an empty stomach when blood sugar and insulin levels are low MAY encourage your body to burn slightly more fat for fuel over carbohydrates. This does NOT mean that you burn more calories or lose more total body fat. Exercising with low muscle glycogen levels means you may fatigue sooner and/or reduce your exercise intensity, doing fewer reps/ sets or using lighter weights. Ironically this may result in you burning fewer calories and less bodyfat!

Worse again, you could end up losing your hard-earned muscle as you may start burning protein, as well as fat for fuel.




Red-S or Relatively energy deficiency in sport, refers to when an athlete or physically active individual does not have enough energy available relative to the amount of activity that they are partaking in.

It occurs when an exercising individual does not consume enough food to support the energy expenditure that is needed by their training and other daily activities (breathing, digestion, brain function). Negative effects on the body include:

  • Impaired athletic performance which may result in reduced endurance, increased injury risk, decreased training response and impaired judgement.
  • Health consequences which can cause impairments of metabolic rate, menstrual function, bone health, immunity, protein synthesis, and cardiovascular health. Hormonal implications may lead to irregular or absent menstrual periods, while in males may cause decreased testosterone levels.



Take home message


Cutting your caloric intake by a slight 15% will produce steady weight loss without sacrificing significant muscle loss. You can expect to lose about 0.5kg/week, slightly more when combined with the correct cardiovascular training which may be prescribed by your trainer! If you have or are planning to increase your training load in preparation for competition for example – it may be worth being proactive in planning food intake. Paying attention to energy levels and making a cautious effort to consume enough energy per day is required. Any questions talk to our nutritionist here at Authentic Personal Training.


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