Carbohydrates are one of the 3 groups of macronutrients that provide the energy needed for everyday activity and metabolism. However, they have been demonised for a long time, as they’re considered the most fattening. In fact, when I ask my patients what type of nutrient is the most fattening, in 90% of cases the answer is “carbohydrates”.
The reason behind this is that people associate them with clearly calorie-rich products like sweets, rice, chips and so on. These foods have 50% more calories due to the presence of fats, which are more fattening than carbohydrates and proteins. Fats also double the intake of kilo-calories (1g of carbohydrates provides 4 kcal, while 1 g of fat is equivalent to 9 kcal).
So, we need to take a set of different parameters into account:
Simple and complex carbohydrates
Each one acts very differently when they enter our body, changing the end result of the caloric balance.
Simple carbs are made up of one or two carbohydrate molecules. The most well-known are:
- Monosaccharides: glucose, fructose (fruit) and galactose.
- Disaccharides: sucrose (table sugar), lactose (milk) and maltose.
Complex carbs (or polysaccharides) are made up of long chains of monosaccharides. The main ones are starch, glycogen and cellulose and they’re found in vegetables, whole grains and the like.
The main difference between the two, in addition to their structure, is that our bodies need to convert complex carbs into simple ones to obtain energy, whereas the body uses simple carbs directly as a source of energy, storing what it doesn’t need as a reserve for when caloric intake is insufficient.
The glycaemic index and carbohydrates
The glycaemic index is the ability of a given carbohydrate to increase the level of sugar in the blood, both in terms of quantity and speed. So when you consume a carbohydrate with a high glycaemic index, it will increase blood sugar levels quickly and significantly. The body reacts in parallel to this by secreting insulin, whose function is to use glucose as a source of energy. However, if the increase in glucose is greater than needed, insulin is responsible for storing the excess inside the cells as a reserve, causing weight gain if the situation occurs frequently.
In the case of complex carbohydrates, the glycaemic index is low, as the body needs to transform these carbs into simple ones, so the increase in blood glucose will be more durable and less pronounced, and the body will gradually obtain energy according to its needs.
In conclusion, if you want to maintain your body weight, you should follow a balanced diet based on unprocessed products and avoid added sugars (found in juices, soft drinks, pastries and white bread). Plus, simple sugars (rice, potatoes and pasta) should be eaten in moderation and a greater emphasis should be place on consuming fruit and complex carbohydrates (vegetables and whole grains).
In fact, the key is to eat healthily and follow the nutritionist’s instructions to ensure a varied diet that provides the nutrients your body needs.
Dr. José Manuel Romo González
Nutrition Specialist
Medical Director at Obesmedica Clinic
