Examining commonalities and differences in food groups, nutrients, and diet quality among popular diets

The US News and World Report (USNWR) conducts an annual review of popular diets: Moderate (reducing energy intake from all food groups, particularly those high in fat and added sugars); Plant-based (excluding food groups, such as animal products); Low-carbohydrate (excluding/limiting carbohydrate-containing foods); and Meal-replacement diets (replacing foods with pre-made, calorie-controlled portions). The goal of this paper was to examine how these diets differ in nutrients, food groups, and diet quality.

This study examined the 40 diets rated by physicians and nutritionists for the 2018 USNWR and assessed differences among diets that were categorized by two independent reviewers: Moderate (n = 15), Plant-based (n = 12), Low-carbohydrate (n = 8), and Meal replacement (n = 5). Nutrient, food groups, and diet quality (Dietary Inflammatory Index (DII®), Healthy Eating Index (HEI)) were assessed from the 2018 USNWR.

There were significant differences among the four diet types for energy; % energy from saturated fat, carbohydrates, and protein; trans fat; sugars; fiber; magnesium; cholesterol; HEI; fruit; total fruit and vegetables; whole grains; total grains; total meat; nuts and seeds; legumes; and total protein foods. Plant-based and Moderate diets, especially the Macrobiotic, Big Loser and Ornish diets, had strongly anti-inflammatory DII scores (-4.82, -4.85 and -4.06, respectively). Moderate (86.9 ± 7.7) and Plant-based (86.1 ± 10.7) diets had significantly higher HEI scores than Low-carbohydrate diets (70.6 ± 15.0; P = 0.01).

These findings provide useful information on nutrient adequacy of popular diets. Results indicate that Plant-based and Moderate diets have better dietary quality (HEI, DII) and better nutrient and food group profiles than Low carbohydrate diets.