Low-carb and low-fat diets show similar heart health patterns. Digest
For decades, nutrition debates have often centered on whether people should cut carbohydrates or cut fat. A new study examined how low-carbohydrate and low-fat diets were associated with heart disease risk when the quality and sources of the foods people ate were taken into account.
You just missed this in your inbox
Every other week our Premium Members received this exact study plus Rhonda's practical commentary and 8+ other hand-picked papers.
The researchers analyzed data from 198,473 men and women in three long-running health studies in the United States. Participants were free of diabetes, cardiovascular disease, and cancer at the start, and completed detailed diet questionnaires about every four years over periods spanning more than 30 years. Rather than simply comparing low-carbohydrate and low-fat diets, the researchers separated these eating patterns into healthier and less healthy versions based on the foods people ate. They then tracked new cases of coronary heart disease and, in smaller groups of participants, examined blood markers related to cholesterol, triglycerides, inflammation, and metabolism.
- Higher-quality lower-carbohydrate diets were linked to a 15% lower rate of coronary heart disease. The defining features of these diets were fewer refined grains, added sugars, and potatoes, along with a greater reliance on plant-derived sources of fat and protein.
- Higher-quality lower-fat diets were linked to a 13% lower rate of coronary heart disease. These diets emphasized whole grains, fruits, legumes, and other higher-quality carbohydrate foods, along with more plant protein and less animal fat.
- Lower-quality lower-carbohydrate diets were linked to a 14% higher rate of coronary heart disease. These diets contained more animal fat and animal protein and fewer whole grains, fruits, legumes, and nonstarchy vegetables.
- Lower-quality lower-fat diets were linked to a 12% higher rate of coronary heart disease. These diets emphasized refined carbohydrates and animal protein while containing less vegetable fat.
The biomarker findings pointed to common patterns despite the different carbohydrate and fat targets. People whose eating habits most closely matched the healthier versions of these diets tended to have lower triglycerides, higher HDL cholesterol, and lower levels of an inflammation marker. LDL cholesterol and non-HDL cholesterol did not clearly differ across the dietary patterns. One possible explanation for these findings is that the healthier low-carbohydrate and low-fat diets shared many of the same food characteristics despite their different labels. Both tended to emphasize higher-quality carbohydrate sources while containing lower amounts of refined carbohydrates, saturated fat, trans fat, and processed meat. That overlap may help explain why the two healthier approaches showed similarly lower rates of coronary heart disease.
The findings are observational, so they cannot show that the eating patterns caused the differences in heart disease risk. Still, the study suggests that rather than focusing on a single macronutrient or dietary extremes, it is more useful to build a diet around minimally processed foods rich in vitamins, minerals, fiber, and other beneficial compounds. In this clip, I break down what I eat in a day.