Medical Nutrition Therapy for Diabetes MellitusManual of Clinical Nutrition Management C- 11 Copyright © 20 13 Compass Group, Inc.
Energy Balance, Overweight, and Obesity in Diabetes
Overweight and obesity affect insulin resistance and metabolic outcomes; therefore, weight loss is
recommended for persons with diabetes who are overweight or obese as well as persons at risk for
developing diabetes who are overweight or obese (1,2,4). Short-term studies have demonstrated that weight
loss in subjects with type 2 diabetes is associated with decreased insulin resistance, improved measures of
glycemia and dyslipidemia, and reduced blood pressure (Grade II) (4). The evidence-based nutrition guidelines
encourage setting goals for a reasonable body weight, defined as a weight that the patient and the health care
team acknowledge as being achievable and maintainable (1,2,4). A weight loss of 5% to 10% from baseline has
positive effects on metabolic outcomes. The body mass index may be used to identify healthy weight ranges
and estimate the desirable body weight. National guidelines for weight management can be applied to
persons with diabetes who are overweight or obese and for whom weight loss is a primary health outcome
(1,48). For patients with type 2 diabetes who have a BMI > 35 kg/m^2 , bariatric surgery should be considered
especially if the diabetes is difficult to control with lifestyle and pharmacologic therapy (1). Refer to Section
IB: Nutrition Management of Bariatric Surgery.
A standard weight-loss diet that adjusts total energy intake to achieve an energy deficit of 500 to 1,000
kcal/day will initially achieve 1 to 2 lb of weight loss per week (48). Although many people can lose weight (as
much as 10% of initial weight in 6 months) with these standard diets, without continued support and follow-
up, people usually regain the weight that was lost (2,48). Low-fat, low-energy diets have traditionally been
promoted for weight loss; however, three randomized controlled trials found that subjects on low-
carbohydrate diets lost more weight at 6 months than subjects on low-fat diets (49-51). A meta-analysis
showed that at 6 months, low-carbohydrate diets were associated with greater improvements in triglycerides
levels and high-density lipoprotein cholesterol concentrations than low-fat diets; however, the LDL
cholesterol level was significantly higher on the low-carbohydrate diets (52). A more recent meta-analysis of
restricted-carbohydrate diets in patients with type 2 diabetes revealed similar findings, with the exception of
elevated LDL levels (53). The analysis showed that a decrease in carbohydrate intake from 65% to 35% of
total energy yields an expected decrease of approximately 23% in the triglycerides level (53). A comparison of
the studies demonstrated variable carbohydrate intakes (4% to 45% of total energy), and in most studies the
carbohydrate intake fell below the Recommended Daily Allowance of 130 g/day (53). The authors concluded
that a lower-carbohydrate diet can be beneficial in treating type 2 diabetes due to beneficial effects on the
levels of glucose, A1C, and triglycerides; however, the impact of these diets on cardiovascular outcomes
remains to be determined (53).
In a majority of studies, a low-carbohydrate diet begins with an induction phase of <30 g of carbohydrate
per day with incremental increases to achieve ~30% to 40% of energy from carbohydrate (54). The American
Diabetes Association recommends either a low-carbohydrate or low-fat, energy-restricted diet as an effective
option for short-term (up to 1 year) weight loss in overweight and obese persons with type 2 diabetes (1,2).
However, the American Diabetes Association does not recommend a low-carbohydrate diet in which the total
carbohydrate intake is restricted to less than 130 g/day (2,53). Low-carbohydrate diets are broadly defined in
the literature; the macronutrient composition from carbohydrate ranges from 4% to 45% in these diets (53).
A review of popular diets by the U.S. Department of Agriculture defined a low-carbohydrate diet as containing
<30% of energy from carbohydrate, a medium-carbohydrate diet as 30% to 55% of energy from
carbohydrate, and a high-carbohydrate diet as >55% of energy from carbohydrate (54). Because considerable
variations exist for low-carbohydrate diets, it is important for the dietitian to work collaboratively with the
physician and patient in designing an optimal meal pattern that best supports desired metabolic outcomes.
When prescribing a low-carbohydrate diet to diabetic patients, it is prudent to provide a carbohydrate
amount that meets the Recommended Daily Allowance of 130 g/day because lower intakes eliminate many
foods that are important sources of energy; fiber; water-soluble vitamins folate, thiamin, and pyridoxine; fat-
soluble vitamins A and E; and minerals including calcium, potassium, and magnesium (53). The safety
concerns that surround low-carbohydrate diets include increased uric acid levels in gout patients as well as
other related side effects including constipation, diarrhea, dizziness, halitosis, headaches, and insomnia (55,56).
Low-carbohydrate diets may not be suitable for children, reproductive-age women, and hypertensive
individuals (55). In addition, the American Diabetes Association does not advocate the use of high-protein
diets due to increased risks of glomerular hyperfiltration and accelerated renal complications associated with
diabetes (2,53). Therefore, the ratio of protein generally should not exceed 20% of total energy when
determining the macronutrient distribution for a low-carbohydrate meal plan. Patients who are prescribed a
low-carbohydrate meal plan should be closely monitored and have frequent assessments of their lipid profile,
renal function, protein intake, urine levels of ketones and glucose, as well as uric acid levels in patients at risk
for gout. In addition, the hypoglycemic risk must be assessed to prevent episodes of hypoglycemia (1,2).