Why it is not Wise to Eat Less Fat?
According to two international studies, people who eat too much carbohydrate and too little fat have a higher risk of mortality and cardiovascular disease.
A study conducted on a very large population suggests that we should not overconsumption carbohydrates, especially those that are refined at the expense of fat. The results are published in The Lancet. The data were collected during the PURE study ( Prospective Urban Rural Epidemiology ), a large epidemiological survey conducted seriously on 135,335 participants aged 35 to 70 years and living in 18 different countries. Participants responded to food questionnaires. The follow-up lasted approximately 7.4 years. The aim of this study was to study the associations between diet – and more particularly fats and carbohydrates – and cardiovascular diseases or even cardiovascular, non-cardiovascular and total mortality.
- Those with the highest carbohydrate intakes (74.4-80.7% of daily calories) have a total mortality risk increased by 28% compared to those with the lowest intakes.
- For carbohydrate intakes between 65.7% and 69.7% of total calories, the risk is 17%.
- For carbohydrate intakes between 59.3% and 62.3%, the risk is no longer significant.
- The risk of non-cardiovascular death is also higher for people who consume more than 65.7% of calories in the form of carbohydrates, compared to those who consume the least.
- However, no association has been found for carbohydrates with the risk of cardiovascular disease and death.
- Participants with the highest fat intakes had a 23% lower mortality risk than those with the lowest intakes. This reduced risk was about “good” fats (monounsaturated and polyunsaturated), but also, and a little counter-intuitive, saturated fats (animal fats, vegetable fats tropical), often vilified. People who consumed the most saturated fat even had a risk of stroke reduced by 21% compared to those who consumed the least (significant association, but little).
Ecological study in 158 countries leads to similar results
In March 2018, a Czech study published in Nutrients also associates high carbohydrate consumption and the risk of cardiovascular disease. Researchers used food and health data from 158 countries (all over the world), long-term statistics (18 years) by FAO (United Nations Food and Agriculture Organization), and WHO (World Health Organization) and not questionnaire data. The consumption of 60 foods chosen as good representatives of the protein, fat, carbohydrate and calorie intake of all countries studied. Results: The factors related to cardiovascular diseases showed a strong association with a high consumption of carbohydrates, in particular in the form of cereals with high glycemic index and in particular wheat. Other foods associated with cardiovascular risk were alcohol (distilled) and sunflower oil. High cholesterol levels, on the other hand, were associated with a lower risk of cardiovascular disease.
What conclusions can be drawn from these studies?
First, it should be noted that the PURE study is certainly a rigorously conducted study, but it remains an observational study, reporting associations between diet and health, without we can talk about cause-and-effect. Second, the study focused on countries with widely varying economic development and dietary habits. High carbohydrate consumption comes from countries and regions that rely on monocultures that provide low-cost energy such as rice (often refined). Remarks also valid for the ecological study on 158 countries.
One of the lessons learned from these studies is that overeating carbohydrates is probably not a good thing if you do not exercise intensively. We advise since 2006 in The Best Way of Eating, that these nutrients account for 40 to 55% of daily calories, preferably in the form of little processed foods. The authors of this study estimate that intakes of the order of 50-55% of calories are more appropriate than consumptions too low or too high.
These two studies also contribute to forging another point of view on fats. For several decades, health authorities and nutritionists in many countries have explained that fats are the enemies of health, that they block the arteries and that we must eat “less fat”. Even when it is recognized that a fat is beneficial, we advise not to eat too much. For example, the Nutriscore adopted to report good and bad foods, penalizes fatty foods. ” The body needs fats, write the authors. They carry vitamins and provide essential fatty acids. Fats play a role in the body, especially in terms of hormones. Reducing fat intake to very low levels exposes to harmful deficits .
However, in recent years there has been a shift in the ANSES discourse on fats. Initially set at 30-35% of calories, the share of fat has been reassessed to 35-40%, about what we advise (30-40%). The PURE study suggests that average fat intake of about 35% of daily calories is associated with low mortality.
Should we avoid saturated fats, often pointed at? These and other studies suggest that you can consume 10-13% of your calories in the form of saturated fats without risking or even profiting. For comparison, we have been proposing that saturated fats represent 10 to 12% of total calories. In the PURE study, the highest consumption range was 11.9-15.1% (mean: 13.2%).
When people try to reduce fats, they often replace them with carbohydrates and sugars, which increases the risks to their health. ” The ideal would be to” relax “the restriction on intake of total fat and saturated fats but instead to limit carbohydrates and, if the contributions are high, return to more moderate intakes,” they conclude.