Level 1: Likely reliable evidence
A randomized trial evaluated the efficacy of a portion-control strategy (a specially designed dinner plate and breakfast bowl) on weight loss (Arch Intern Med. 2007;167:1277-1283). Researchers randomized 130 obese patients with type 2 diabetes to use of the portion-control plate vs. usual care alone for six months. Usual care consisted of patient education by a dietitian. Plate sizes were gender-specific and designed to provide about 800 kcal per meal for men and 650 kcal per meal for women; the breakfast bowl was designed to provide about 200 kcal per meal.
The portion-control plate was associated with greater mean weight loss (2.1 kg vs. 0.1 kg [4.63 lb vs. 0.22 lb], P=.01), greater mean percentage weight loss (1.8% vs. 0.1%, P=.006), and more patients achieving ≥5% weight loss (16.9% vs. 4.6%, P=.048, NNT 9). There was no significant difference in mean change in hemoglobin A1c level (+0.22% vs. -0.2%). More patients using the plate were able to decrease their hypoglycemic medication (26.2% vs. 10.8%, P=.04); 13.8% vs. 33.8% who had an increase in hypoglycemic medication (P=.01).
The dishes used in this study cost $35 for the plate and $31.50 for the cereal bowl (www.thedietplate.co.uk; accessed January 10, 2008).