Diets rich in whole grains, legumes, nuts, and fruit are linked with a lower risk of overweight and obesity, finds a comprehensive new study (1).

The first-of-its-kind umbrella review summarised the available evidence on the link between the intake of various food groups and risk of overweight and obesity.

It considered the findings from observational studies and trials on adults, for 14 ‘food groups’: whole grains, refined grains, fruit, vegetables, nuts, legumes, fish, eggs, total dairy, red meat, white meat, processed meat, added sugar, and sugar-sweetened beverages

Thirteen articles were included in the umbrella review.

For each food group, data included an average (mean) of 166,100 participants, and 36,760 cases – with the highest number of participants for the nut studies.

Did you know? Umbrella reviews collate the findings from earlier systematic review and meta-analysis research to provide the best quality and most up-to-date evidence for a research topic. 

The main findings:

• High intakes of whole grains, nuts, legumes, and fruit were associated with a lower risk of overweight/obesity.
• High intakes of red meat and sugar-sweetened beverages were associated with an increased risk of overweight/obesity.
• No significant results were found for the remaining food groups.
• Further research is needed on the association between the intake of fish, eggs, white meat, and added sugars and overweight/obesity, as data (systematic reviews and meta-analyses) is lacking.

Many of the foods associated with a reduced risk of overweight/obesity are plant foods. This aligns with dietary guidelines emphasising plant foods, like fruit, legumes, nuts and whole grains, as part of healthy dietary patterns (1).

Limitations of the umbrella review include that for some of the food groups, such as legumes and red meat, few studies were available, contributing to uncertainty.

And heterogeneity was generally high for most food groups, except whole grains and sugar-sweetened beverages, which might indicate that there is substantial variation with the findings of the included studies, within each food group.

The umbrella review was recently published in the journal Nutrients.

Did you know? A major systematic review and meta-analysis on nuts and weight, which was included in this umbrella review, found a ‘high certainty’ of no adverse effect of nuts on body weight (2).

The bottom line:

The findings of this comprehensive review reveal that diets rich in whole grains, legumes, nuts and fruit are associated with a lower risk of developing overweight or obesity. These findings generally align with dietary guidelines and strengthen the evidence for recommending diets rich in plant foods.

Did you know? A serve of nuts is 30g, or about one handful. But research suggests that up to 120g can be eaten daily, without gaining weight (3).