Are calories really important during weight loss?

Likewise, fructose tends to increase ghrelin levels more than glucose. It also doesn’t stimulate the fullness centers in your brain in the same way as glucose, so you won’t feel as full after eating fructose as you do after eating glucose.

This is why most processed foods that are high in fructose but devoid of protein or fiber generally make it difficult for you to maintain an energy balance.

Calorie source has different effects on your metabolism
Foods affect metabolism differently. For example, some require more work for digestion, absorption, or metabolism than others. The scale used to estimate this action is called the thermodynamic effect (TEF).

The higher the TEF, the more energy the food needs to be metabolized. Protein has the highest percentage of TEF, while fat has the lowest. This means that a high-protein diet requires more calories to be metabolized than a low-protein diet.

This is why eating protein is often said to boost your metabolism to a greater extent than eating carbohydrates or fats. However, when it comes to weight loss, TEF foods seem to have only a minimal effect on calorie balance.

Why is nutrient density important
The amount of nutrients a food contains per calorie can vary greatly.
Nutrient-rich foods provide higher amounts of vitamins, minerals and beneficial compounds per gram than foods that are less nutrient-dense.

For example, fruit is more nutrient dense than cake. Calorie for calorie, fruit will provide a much larger dose of vitamins, minerals, and beneficial plant compounds.