Persons with abdominal obesity have a high prevalence of endothelial dysfunction, arterial stiffness, and left ventricular diastolic function, each an early marker of cardiovascular disease (CVD). Though diet and exercise are primary treatments for obesity, less is known about the effects of different weight loss regimens on CV health. Randomized trials show that a lowcarbohydrate diet, and thereby a higher fat diet is efficacious for weight loss and concerns about adverse CV effects resulting from such a diet were not substantiated as subjects improved CVD risk factors. These trials provide a strong rationale for a low-carbohydrate diet despite a general lack of endorsement for such a diet in consensus guidelines. Because most weight loss guidelines recommend that a weight loss diet should be combined with exercise, this 6-month study addresses the effects of two different diets combined with exercise on CV health. Participants will be randomized to a low-carbohydrate diet or a low-calorie, low-fat diet, each combined with supervised exercise training. Even if the low-carbohydrate approaches reduces weight, does a greater percentage of dietary fat calories boost or hinder improvements in CV structure and function? What are the effects of each intervention on risk body composition, insulin levels, inflammation, oxidative stress, blood pressure, lipids, and other a risk factors for CVD? All of the benefits of exercise should magnify the benefits of weight loss on CV parameters but this combination with different diets has not been studied. The overall aim is to test the hypothesis that each intervention will improve endothelial dysfunction, arterial stiffness, and left ventricular diastolic function. We also hypothesize that improvement in CV parameters will be associated with favorable changes in body composition, inflammation, insulin levels, lipids, blood pressure, and fitness. The findings will have important clinical implications for the role of different diets combined with exercise for improving CV structure and function and reducing CVD risk
Obese persons have abnormalities in cardiovascular structure and function that appear before a person suffers from a cardiac event such as a heart attack or develops heart failure. Recent studies show that low-carbohydrate diets, which by definition are higher in dietary fat than conventional lowcalorie, low-fat diets, are effective for weight loss and are safe in terms of cardiovascular disease risk factors and exercise training is broadly recommended to accompany a weight loss diet not only for enhancing weight loss but also for its beneficial effects on cardiovascular health. This 6-month study will examine if a low-carbohydrate diet plus exercise compared with a low-calorie, low-fat diet plus exercise improves cardiovascular parameters that are early markers of heart disease in persons with abdominal obesity, and positive findings would recognize more choices for weight loss and reducing cardiovascular disease risk.
