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Tuesday, March 3, 2015
It's still too early to tell if popular diets that focus on eliminating some essential nutrients while loading up on others will lead to long-term health benefits. Diet plans, such as the Atkins, (low-carbohydrate, high-fat) and Ornish (low-fat, high-carbohydrate) diets, have stirred a debate about the health effects of macronutrient distribution in the diet.
With the rise of obesity and diabetes, there is concern about whether popular diets are the best prescriptions for optimal health. There's an intense debate about the ideal combination of carbohydrate, protein and fat for effectively managing obesity and its metabolic consequences such as diabetes, and for improving body composition and overall health.
But it's difficult to reach an agreement when there's been a lack of long-term studies to determine the benefits and risks of each diet.
In studies published over the last 20 years, researchers found that while low-carb, fad diets may help shed pounds and lower cardiovascular risks in the short term, longer studies are needed to fully determine if these diets are really effective and safe, and whether they warrant nutritional recommendations from health providers.
The studies examined provided additional, but not yet sufficient, evidence for modification of current nutritional guidelines, which suggest how much fat, protein and carbohydrate a person should consume to lose weight or improve their overall health. Despite a recent flurry of research, many fundamental questions related to dietary macronutrients and their effects on energy balance and metabolism remain unanswered.
Macronutrients (carbohydrate, protein and fat) are nutrients the body needs in large quantities to provide energy for normal functions.
The diets reviewed were either low in carbohydrate or high in monounsaturated fat or the "good fats" generally known to reduce "bad" cholesterol levels in the blood and lower the risks of heart disease and stroke.
While each diet claims to offer a distinct health benefit over another, some may come with associated risks, which might not be worth taking in the long run.
Evidence shows that low-carbohydrate diets lead to weight loss in 12-month studies, but these same studies showed that these diets don't affect everyone's metabolism the same way and there’s potential for increased LDL-cholesterol or the "bad" cholesterol.
The medical community traditionally has supported moderately low-fat, high-carb diets for cardiovascular health, but the success of these diets has only recently been tested in well-designed clinical studies.
The unceasing demand by patients and health care providers for effective weight-loss methods has led to the use of a wide number of unproven strategies. A year might seem long for those conducting or participating in a study, but it comprises only a short time in the life of an overweight person. In essence, the long-term benefits remain unknown.
The same can be said for high-monounsaturated fat diets, such as those typical of the Mediterranean region. While these diets may help manage cardiovascular risk, there's a steadfast belief among health practitioners that high-fat diets may cause increased energy intake and weight gain. However, recent studies have shown that high-monounsaturated fat diets are associated with at least as much weight loss as lower-fat diets.
Until more long-term research is conducted, it is recommended that one should stick with the diet recommendations of expert bodies such as the
These are based on clinical expertise and scientific data by groups of leading practitioners.
This article originally appeared in UC Health Line (5/1/08), a service of the University of Cincinnati Academic Health Center Public Relations Department and was adapted for use on NetWellness with permission, 2006.
Last Reviewed: May 08, 2008
Bonnie J Brehm, PhD, RD
Professor of Nursing
College of Nursing
University of Cincinnati