Grain Exercise Trial - Whole Grain Versus no Grain With or Without Physiotherapy-promoted Exercise for Waist Loss

Overview

The main purpose of this 2-year lifestyle experiment for waist loss is twofold: 1. to compare whole grains and no grains as part of a healthy diet, 2. to determine if an 8-week exercise program, led by physiotherapists, is more efficient than brief counseling and follow-up. People with abdominal overweight (≥84 cm in women and ≥98 cm in men) and at least one additional cardiovascular risk factor, (typically hypertension, diabetes type 2 or prior cardiovascular disease) are randomly assigned to receive Diet A or Diet B, with or without a structured exercise program at the department of physiotherapy, or to a control group receiving usual care. Diet A and B both include fruit, vegetables, fish, meat, and low-fat dairy products, and differ only in that Diet A recommends exchange of cereal grains for more potatoes, root vegetables, fruit and other carbohydrate-rich foods, while Diet B recommends exchange of regular cereal grains for whole grains. The primary outcome (most important follow-up variable) is change in waist circumference during 2 years. Secondary outcome measures include blood pressure, blood lipids, level of physical activity and, in subjects with diabetes, glycated hemoglobin and fasting blood sugar.

This is a randomized controlled trial with 5 parallel groups of approximately equal size. Two hundred subjects with increased waist circumference (≥84 cm in women and ≥98 cm in men) and at least one additional cardiovascular risk factor will be included. Four of the 5 groups will receive dietary advice (A or B) and 2 of them will be allocated to physiotherapy. A fifth control group will only receive usual care in addition to follow-up. Randomization will be performed by use of an internet-based random number generator from the School of Computer Science and Statistics, Trinity College, Dublin (www.random.org). randomly assigned to receive Diet A or Diet B, with or without a structured exercise program at the department of physiotherapy, or to a control group receiving usual care. In addition to primary (waist loss) and secondary outcome measures as given below, a health questionnaire will be performed at baseline and after 12 and 24 months with questions about general health, self-reported quality of life, medication use, living habits, physical activity, nutrition, tobacco, alcohol, personal motivation and perceived ability to change lifestyle. Furthermore, serum creatinine will be measured at baseline, and after 3, 6, 12 and 24 months. There are few randomized controlled trials comparing the effect of different lifestyle interventions on physical activity level or weight loss in overweight people at high risk of cardiovascular disease. There is no such study of the possible effect of a structured exercise program with group training led by physiotherapists, with the exception of rehabilitation programs after myocardial infarction. In addition, the possible unique effect of cereal grains on satiety and energy intake has not been addressed in randomized controlled trials. In two earlier studies in glucose intolerance and diabetes type 2, we have applied a dietary model (Paleolithic diet) based on root vegetables, fruit, vegetables, meat and fish, partly at the expense of cereal grains (Lindeberg et al., 2007; Jönsson et al., 2009). The results showed a more beneficial effect on waist circumference than from traditional dietary advice. In one of the studies in 29 overweight men with coronary heart disease and impaired glucose tolerance, the decrease of waist circumference was 2.7 cm greater (p=0,03) in the intervention group (-5.6 cm; 95% confidence interval \[CI\] -7.2;-3.9) than in the control group (-2.9, CI -4.8;-1.1) during 3 months of follow-up (Lindeberg et al., 2007). In the second study, where the same dietary model was applied in cross-over design among 13 subjects with diabetes type 2, waist circumference decreased 4 cm more (p=0,02) during the intervention diet than during the control diet (Jönsson et al., 2009). There is some evidence to suggest that cereal grains may interfere with leptin receptor activity in a way that could hypothetically suppress satiety (Jönsson et al., 2005; Kamikubo et al., 2008).