Back to blog


Back to blog

Whether you want to lose weight or build some lean muscle, you need to consider the amount of food you’re eating. However, it’s not actually the quantity of food that’s important but the number of calories that food contains. You could eat a big pile of food that contains very few calories, eg. leafy green vegetables, or a small portion of food that contains a lot of calories – such as candy.

The number of calories in your food is arguably more important than how much food you eat.


A calorie is a unit of energy, that has been used to track food intake. One calorie is the amount of energy required to raise the temperature of one gram of water by one degree centigrade. 1000 calories make a kilocalorie which, confusingly, is what most people call a calorie. Food labels list kilocalories which should really be called Calories – with a big C – to differentiate them from calories – with a small c.

Confused? Just remember there are 1000 calories in a single Calorie and nutritional labels list Calories and not calories!


The human body needs the energy to survive, and that energy comes from the food you eat. Excess food that is surplus to your current energy requirements is converted to body fat. This is called a positive energy balance.

If you keep on eating more energy than you need, your fat stores will continue to increase, and you’ll keep on gaining weight. However, if you restrict your food intake, your body will use this stored energy, and you’ll lose weight. This is commonly referred to as a negative energy balance. If the energy in equals energy out, your weight should remain stable.


Different food groups contain differing amounts of energy – these are commonly called macronutrients:

  • Protein contains four calories per gram
  • Carbohydrate contains four calories per gram
  • Fat contains nine calories per gram
  • Alcohol contains seven calories per gram

This information could lead you to conclude that fat is bad, alcohol is not quite as bad, and that protein and carbs are interchangeable. This is not actually the case.


Each of the food groups does different things within your body and also requires differing amounts of energy to break them down and utilize them. This is called the thermic effect of food, TEF for short.

It takes more energy to utilize a gram of protein than it does a gram of carbs so, despite containing the same number of calories before digestion, they provide your body with differing amounts once consumed.

The thermic effect of protein is 20-35% whereas the TEF for carbs is 5-15%. The TEF for fat is a lowly 5-10%.

In simple terms, if you eat 100 calories of protein, only 65-80 are usable, and the rest is “lost” in the process of digestion. In contrast, if you eat the same amount of carbohydrate, your body will receive 85-95% of the available calories. This all helps to explain the efficacy of high protein, lower carb diets such as Ketogenic.


While eating more protein and fewer carbs can help you expend more energy and speed up weight loss, you still need to consider the number of calories you are consuming.

Counting calories used to be a real pain in the butt, but now it’s really easy! My online training platform allows you to track all the calories and macronutrients within your meal plan but currently doesn’t track other foods which is where other calorie counting apps come in handy, like My Fitness Pal. Use these features for when you are dining out or simply feel like a different meal.

Tracking calories means that you can control how much food you need to eat for weight loss (or weight gain) and it also makes you more accountable. After all, if you know you are going to have to log that box of six donuts in your calorie tracker, you are much less likely to eat them. However, it is important to note that no calorie tracker takes into consideration the thermic effect of food.

Back to blog