Carbohydrates make you gain weight and increase blood sugars, but also dietary fats may affect the waistline … so, the best diet is low fat/ high carbs or the other way around? The positions are different and often conflicting but a group of scientists of the University of Harvard T.H. Chan School of Public Health and of the Boston Children's Hospital seems to have found an answer to the issue and the results of this study have been published a few days ago on the special number dedicated to nutrition of the prestigious scientific journal Science (Ludwig et al, Science, Nov 2018).
The researches start from a few considerations:
Substituting saturated and trans fats, obtained through industrial processes, with unsaturated fats brings benefits to the general population
Substituting refined and highly processed carbohydrates, namely sugars, cereals and potato products, with unprocessed carbohydrates such as whole grain cereals, legumes, whole fruits and nonstarchy vegetables brings benefits for the health
By considering a diet that has replaced saturated and trans fats and refined cereals with less processed products and unsaturated fats and by focusing the attention on healthy people with normal blood sugar levels and without insulin resistance the researchers have claimed that, for a good health and a low risk of developing diseases, the ratio carbs / fats varies in a wide range and that there isn’t a particular, optimal value. While for people with insulin resistance and glucose intolerance the benefits may come from a low carbs diet and a higher intake of unsaturated fats. However, in the case of a low carbs diet, an increase in proteins from animal products isn’t required, but a good choice may be to replace in part cereals and starchy vegetables with nuts, dry fruits, seeds and high fat fruits such as avocado. Other studies are required in order to solve some controversial points remained open, for example in case of a specific ratio carbs / fats what is the relative importance of the classical markers for cardiovascular disease such as LDL, HDL cholesterol and triglycerides?