Low fat/high carbohydrate diet, high fat/low carbohydrate diet, or the type of fat that is consumed, which one matters the most for a healthy life? An overall high-quality diet that is low in sugar and refined cereals with no specific fat to carbohydrate ratio is essential to maintain healthy body weight and low risk to chronic diseases, reveals a team of researchers from Harvard T.H. Chan School of Public Health and Boston Children's Hospital.
"This is a model for how we can transcend the diet wars," said lead author David Ludwig, professor in the Department of Nutrition at Harvard Chan School and a physician at Boston Children's Hospital. "Our goal was to assemble a team with different areas of expertise and contrasting views, and to identify areas of agreement without glossing over differences."
‘‘Avoidance of refined carbohydrates and foods high in sugar help maintain body weight and prevent illnesses’.’
The review was published online November 15, 2018 in Science
The authors laid out the evidence for three contrasting positions on dietary guidelines for fat and carbohydrate consumption:
1. High consumption of fat causes obesity, diabetes, heart disease, and possibly cancer, therefore low-fat diets are optimal.
2. Processed carbohydrates have negative effects on metabolism; lower-carbohydrate or ketogenic (very low-carbohydrate) diets with high fat content are better for health.
3. The relative quantity of dietary fat and carbohydrate has little health significance--what's important is the type of fat or carbohydrate source consumed.
They agreed that by focusing on diet quality--replacing saturated or trans fats with unsaturated fats and replacing refined carbohydrates with whole grains and nonstarchy vegetables--most people can maintain good health within a broad range of fat-to-carbohydrate ratios.
Within their areas of disagreement, the authors identified a list of questions that they said can form the basis of a new nutrition research agenda, including:
1. Do diets with various carbohydrate-to-fat ratios affect body composition (ratio of fat to lean tissue) regardless of caloric intake?
2. Do ketogenic diets provide metabolic benefits beyond those of moderate carbohydrate restriction, and especially for diabetes?
3. What are the optimal amounts of specific types of fat (including saturated fat) in a very-low-carbohydrate diet?
Finding the answers to these questions, the researchers said, will ultimately lead to more effective nutrition recommendations.