The study is published in the Archives of Internal Medicine.
Dr Sue D Pedersen and colleagues at the University of Calgary, Alberta, carried out a randomized controlled trial of commercially available portion control plates and bowls in 2004.
They randomly assigned 130 obese patients of average age 56 with type 2 diabetes mellitus (including 55 patients taking insulin) to one of two groups. One group used a commercially available portion control dinner plate and cereal bowl for 6 months, and the other group had the usual care (dietary assessment and teaching by dieticians).
Although portion size is an important way of controlling calorie intake, the researchers said they were not aware of any randomized contolled studies that evaluated the effectiveness of such a method to control weight loss.
In 1960 only 13 per cent of the US adult population was obese. By the year 2000 this figure had risen to 31 per cent. Type 2 diabetes is often associated with obesity and restricting calorie intake has been shown to reduce weight loss and improve glycemic control in diabetics.
The authors wrote in the study:
"The increasing prevalence of obesity is paralleled by increasing portion sizes in the marketplace."
"Portion sizes are an important determinant of energy intake; the number of calories ingested by subjects at a meal has been directly correlated with the serving size offered," they added.
The dinner plates used in the trial were marked in sections for carbohydrates, protein, cheese and sauce, with the rest left open for vegetables. The sections added up to an 800 calorie meal for men and a 650 calorie meal for women. The patients in the intervention group used the plate for largest meal of the day.
The cereal bowl allowed a 200 calorie meal of cereal and milk. The patients in the intervention group used this plate to measure out their breakfast portion every day.
122 patients remained in the study at the end of the six month period.
The results showed that:
- 16.9 per cent of the patients on portion control lost 5 per cent or more of their body weight over the six months of the study.
- This compares with 4.6 per cent of those in the usual care group.
- Overall, the patients on portion control lost an average of 1.8 per cent of their body weight compared with 0.1 per cent for those who had the usual care.
- More than twice the proportion of patients on portion control required a decrease in their diabetes medication after 6 months compared to the usual care patients (26.2 per cent versus 10.8 per cent).
"Compared with usual care, the portion control tool studied was effective in inducing weight loss. The portion control plate also enabled patients with diabetes mellitus to decrease their hypoglycemic medications without sacrificing glycemic control."
Pedersen and colleagues said the weight loss result was important because:
"A 5 percent weight loss has been shown to be clinically significant in terms of decreasing morbidity and mortality associated with obesity-linked disorders such as cancer and myocardial infarction [heart attack]."
They said the portion control tool used in the study showed comparable results to other studies that used drugs to induce weight loss. They suggested that the portion control method would be effective for anyone who is overweight, not just diabetics.
"This simple, inexpensive tool also enabled obese patients with diabetes mellitus to decrease their hypoglycemic medication requirements. This intervention holds promise for use in overweight populations with and without diabetes mellitus," they wrote.
"Portion Control Plate for Weight Loss in Obese Patients With Type 2 Diabetes Mellitus: A Controlled Clinical Trial."
Sue D. Pedersen, Jian Kang, Gregory A. Kline.
Arch Intern Med. 2007;167:1277-1283.
Vol. 167 No. 12, June 25, 2007
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Written by: Catharine Paddock
Writer: Medical News Today