Most carbohydrates contain four Calories per gram. They can be simple or complex, depending on the number of sugar units they contain. Simple carbohydrates (sugars) contain one sugar unit, while complex carbohydrates (starches and fiber) contain three or more. Simple sugars are absorbed quickly, and raise blood sugar levels rapidly. This spike in blood sugar levels after eating simple sugars may lead to diabetes and cardiovascular disease.
Complex carbohydrates are typically long, multiple-branched chains of sugar units. Complex carbohydrates generally take longer to digest and absorb, because their sugar units first must be separated from the chain. Starch that has been processed into fine particles, such as flour, is much more quickly absorbable than unprocessed foods. Fiber is a complex carbohydrate that accounts for less than the four Calories per gram of other carbohydrates.
Over the last century or so, some people have portrayed carbohydrates as the cause of weight gain, and have promoted low-carbohydrate diets for weight loss. It’s true that refined carbohydrates, such as white flour, white rice, white pasta, and added sugar are stripped of fiber and vital nutrients, and promote diabetes, cardiovascular disease, and cancer. However, most low-carbohydrate diets replace these refined foods with meat, dairy, and eggs, which are also devoid of fiber and low in micro-nutrients. A 2010 study published in the Annals of Internal Medicine suggests that plant protein from vegetables, nuts, beans, and seeds promotes longevity, whereas meat, dairy, and eggs shorten your life, likely because of their lack of fiber, minerals, vitamins, and phytochemicals.
In fact, your body turns excess protein into carbohydrates through a process called gluconeogenesis, so you don’t need to worry about specific amounts of macro-nutrients in any whole food. When you eat a wide range of vegetables, fruits, whole grains, beans, nuts, seeds, herbs, and spices, you will automatically get the nutrients you need.