During periods of weight loss, the body will go through a process known as “metabolic adaptation” in an attempt to prevent you from going into starvation. This means that the more you diet, the more the body will change the energy gap you have created.
To diet you have to make sure you are going into a calorie (kcal) deficit and cause an energy gap within the body. Doing this will start to cause the body to use its fat stores. The basic principles in play when you diet are TDEE (Total Daily Energy Expenditure) vs Energy Input. TDEE consists of four things: BMR (Basal Metabolic Rate), NEAT (Non-Exercise Activity Thermogenesis), TEF (Thermic Effect of Food) and EA (Exercise Activity). These four things combined create our TDEE and account for the amount of kcal we would need to eat on a daily basis to stay at the same weight.
- BMR This is the amount of energy the body would require to maintain current weight if you were to be at rest all day
- NEAT This is all the things you do throughout the day without thinking about, for example fidgeting and moving around
- TEF This is the amount of energy it takes the body to convert food into other energy sources or move it around the body
- EA This accounts for all of the activities that you do like going to the gym, going for a run or any form of exercise you put the body under
How and why the body adapts to slow down your weight loss
The body will always strive to be as close to homeostasis as possible. When dieting you start to throw things out of whack, so depending on how low you are dropping your body fat levels, the harder the body will fight to keep fat stores built up. When weight loss slows it is because you have lost weight and in turn will have less mass and require less energy to keep the body functioning. So, you just need to account for the smaller weight, right? Wrong! The body will overcompensate to try and prevent you from losing too much weight and start to change the requirements of the body in the following steps:
- The efficiency of the body will start to increase, thus requiring a lower amount of calories to do the same actions, the cardio that helped burn 600kcal, may now only burn 400kcal. The amount you fidget and the speed at which you do things will slow down to reserve energy
- The body will also start to increase the Ghrelin hormone which is responsible for making you feel hungry, in an attempt to get you to increase your energy intake
- Alongside this, the hormones that tell us we are full have been shown to be blocked in an attempt to feel hungry
How to use this information to help you diet
It is important to realise that your metabolism is not broken… it’s just doing its job.
If you find that you are hitting a plateau in your diet it can be worthwhile taking a short diet break. A couple of weeks of having your calories at your new maintenance will allow your bodies hormones to come back up to a normal level. You can then carry on with your diet. Losing between 1.5% and 0.5% bodyweight per week is a good place to aim for but excessively harsh dieting could cause plateauing faster and even make it harder to diet again in the future.
So if you’re stuck on your diet and need that helping hand to get going again, why not talk to one of the Fitness Team!