Eat your greens: Mediterranean diet variation may enhance visceral fat reduction Original paper

Visceral fat plays a key role in developing cardiometabolic diseases (e.g., metabolic syndrome and type 2 diabetes) and differentiating between metabolically healthy obesity and metabolically unhealthy obesity.^[1]

A low-carbohydrate Mediterranean diet enhances visceral fat reduction,^[2] and mechanistic evidence suggests polyphenols could strengthen that association. Could supplementing the diet with polyphenol-rich foods and replacing some animal protein intake with them further enhance visceral fat reduction?

In this 18-month randomized trial, 294 participants (average age of 51; average BMI of 31; 88% men, 12% women) with abdominal obesity or dyslipidemia were assigned to one of the following diet interventions, combined with physical activity recommendations and a free gym membership:

• Healthy diet group (HDG): no specific recommendations pertaining to energy intake, macronutrient distribution, or recipes
• Mediterranean diet (MED): 1,500–1,800 kilocalories per day (kcal/day) for men and 1,200–1,400 kcal/day for women; 40% of energy from fat (mainly unsaturated fat); less than 40 grams of carbohydrate per day for the first 2 months, gradually increasing to up to 80 grams per day; and 28 grams of walnuts per day (440 mg of polyphenols per day)
• Green Mediterranean Diet (GREEN): same as MED plus green tea (3–4 cups per day) and 100 grams of frozen Wolffia globosa plant cubes consumed as part of a shake that partially replaced beef or poultry at dinner (1,240 mg of polyphenols per day)

All of the groups were advised to limit their intake of dietary cholesterol, trans fats, saturated fats, simple sugars, and salt and to increase their vegetable intake. Dietary adherence and physical activity were assessed at baseline, 6 months, and 18 months using questionnaires.

The primary outcome was the change in visceral fat (measured using magnetic resonance imaging). The secondary outcomes were changes in body weight, superficial subcutaneous adipose tissue, and deep subcutaneous adipose tissue.

Weight loss was similar between MED and GREEN (−2.7% vs. −3.9%), and both of those groups lost weight compared with HDG, but the decrease in visceral fat was greater in GREEN than MED or HDG (−14.1% vs. −6.0% and −4.2%). After adjusting for changes in body weight, differences in visceral fat reduction remained between GREEN and MED but not between GREEN and HDG. Superficial and deep subcutaneous adipose tissue decreased compared with baseline in all of the groups, with no differences between the groups.

The low proportion of female participants limits the ability to generalize these findings.