Medical Nutrition Therapy

Version 2. Update October 2022.

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  • Healthy eating is important for all Canadians, regardless of body size, weight or health condition. Key messages from Canada’s Food Guide for Healthy Eating can be used as a foundation for nutrition and food-related education (Figure 1). Use evidence-based nutrition resources to give your patients nutrition and behaviour change advice that aligns with their values, preferences and social determinants of health. (Figure 1)
  • There is no one-size-fits-all eating pattern for obesity management. Adults living with obesity may consider various nutrition intervention options that are client-centred and flexible. Evidence suggests this approach will better facilitate long-term adherence. (Table 1, Figure 2)
  • Nutrition interventions for obesity management should focus on achieving health outcomes for chronic disease risk reduction and quality of life improvements, not just weight changes. 5 Table 2 outlines health-related outcomes to support patients/clients in obesity management.
  • Nutrition interventions for obesity management should emphasize individualized eating patterns, food quality and a healthy relationship with food. Including mindfulness-based eating practices that may help lower food cravings, reduce reward-driven eating, improve body satisfaction and improve awareness of hunger and satiety. 6–11
  • Caloric restriction can achieve short-term reductions in weight (i.e.< 12 months) but has not shown to be sustainable long-term (i.e. > 12 months). Caloric restriction may affect neurobiological pathways that control appetite, hunger, cravings and body weight regulation that may result in increased food intake and weight gain.64-66
  • People living with obesity are at increased risk for micronutrient deficiencies including but not limited to vitamin D, vitamin B12 and iron deficiencies. Restrictive eating patterns and obesity treatments (e.g. medications, bariatric surgery) may also result in micronutrient deficiencies and malnutrition. Assessment including biochemical values can help inform recommendations for food intake, vitamin/mineral supplements, and possible drug-nutrient interactions.
  • Collaborate care with a registered dietitian who has experience in obesity management and medical nutrition therapy. 12 Dietitians can support people living with obesity who also have other chronic diseases, malnutrition, food insecurity or disordered patterns of eating.
  • Future research should use nutrition-related outcomes and health behaviours in addition to weight and body composition outcomes. Characterization of population sample collections should use the updated definition of obesity as a chronic, progressive and relapsing disease characterized by the presence of adiposity that impairs health and social well-being rather than BMI exclusively. Qualitative data is needed to understand the lived experience of people with obesity.

  1. We suggest nutrition recommendations for adults of all body sizes should be personalized to meet individual values, preferences and treatment goals to support a dietary approach that is safe, effective, nutritionally adequate, culturally acceptable and affordable for long-term adherence. (Level 4, Grade D)
  2. Adults living with obesity should receive individualized medical nutrition therapy provided by a registered dietitian (when available) to improve weight outcomes (body weight, BMI), waist circumference, glycemic control, established blood lipid targets, including LDL-C, triglycerides, and blood pressure. (Level 1a, Grade A)
  3. Adults living with obesity and impaired glucose tolerance (prediabetes) or type 2 diabetes may receive medical nutrition therapy provided by a registered dietitian to reduce body weight and waist circumference, and improve glycemic control and blood pressure. (Level 2a, Grade B)
  4. Adults living with obesity can consider any of the multiple medical nutrition therapies to improve health-related outcomes, choosing the dietary patterns and/or food-based approaches that support their best long-term adherence:
    • Calorie-restricted dietary patterns emphasizing variable macronutrient distribution ranges (lower, moderate, or higher carbohydrate with variable proportions of protein and fat) to achieve similar body weight reduction over 6-12 months. (Level 2a, Grade B)
    • Mediterranean dietary pattern to improve glycemic control, HDL-cholesterol and triglycerides (Level 2b, Grade C), reduce cardiovascular events (Level 2b, Grade C,), reduce risk of type 2 diabetes; (Level 2b, Grade C); and increase reversion of metabolic syndrome (Level 2b, Grade C) 21 with little effect on body weight and waist circumference. (Level 2b, Grade C)
    • Vegetarian dietary pattern to improve glycemic control, established blood lipid targets, including LDL-C, and reduce body weight, (Level 2a, Grade B), risk of type 2 diabetes (Level 3, Grade C) and coronary heart disease incidence and mortality. (Level 3, Grade C)
    • Portfolio dietary pattern to improve established blood lipid targets, including LDL-C, apo B, and non-HDL-C (Level 1a, Grade B), CRP, blood pressure, and estimated 10-year coronary heart disease risk. (Level 2a, Grade B)
    • Low-glycemic index dietary pattern to reduce body weight (Level 2a, Grade B) glycemic control; (Level 2a, Grade B); established blood lipid targets, including LDL-C (Level 2a, Grade B), and blood pressure (Level 2a, Grade B)  and the risk of type 2 diabetes (Level 3, Grade C) and coronary heart disease. (Level 3, Grade C)
    • Dietary Approaches to Stop Hypertension (DASH) dietary pattern to reduce body weight and waist circumference; (Level 1a, Grade B); improve blood pressure (Level 2a, Grade B), established lipid targets, including LDL-C (Level 2a, Grade B), CRP (Level 2b, Grade B), glycemic control; (Level 2a, Grade B); and reduce the risk of diabetes, cardiovascular disease, coronary heart disease, and stroke. (Level 3, Grade C)
    • Nordic dietary pattern to reduce body weight (Level 2a, Grade B) and body weight regain; (Level 2b, Grade B) improve blood pressure (Level 2b, Grade B) and established blood lipid targets, including LDL-C, apo B, (Level 2a, Grade B), non-HDL-C (Level 2a, Grade B) and reduce the risk of cardiovascular and all-cause mortality. (Level 3, Grade C)
    • Partial meal replacements (replacing one to two meals/day as part of a calorie-restricted intervention) to reduce body weight, waist circumference, blood pressure and improve glycemic control. (Level 1a, Grade B)
    • intermittent or continuous calorie restriction achieved similar short-term body weight reduction. (Level 2a, Grade B)
    • Pulses (i.e. beans, peas, chickpeas, lentils) to improve body weight; (Level 2, Grade B)  improve glycemic control, (Level 2, Grade B), established lipid targets, including LDL-C, (Level 2, Grade B), systolic BP (Level 2, Grade C), and reduce the risk of coronary heart disease (Level 3, Grade C).
    • Vegetables and fruit to improve diastolic BP (Level 2, Grade B), glycemic control (Level 2, Grade B) and reduce the risk of type 2 diabetes (Level 3, Grade C) and cardiovascular mortality. (Level 3, Grade C)
    • Nuts to improve glycemic control, (Level 2, Grade B) established lipid targets, including LDL-C (Level 3, Grade C), and reduce the risk of cardiovascular disease. (Level 3, Grade C)
    • Whole grains (especially from oats and barley) to improve established lipid targets, including total cholesterol and LDL-C. (Level 2, Grade B)
    • Dairy foods to reduce body weight, waist circumference, body fat and increase lean mass in calorie-restricted diets but not in unrestricted diets (Level 3, Grade C) and reduce the risk of type 2 diabetes and cardiovascular disease. (Level 3, Grade C)

5. Adults living with obesity and impaired glucose tolerance (prediabetes) should consider intensive lifestyle interventions that target a 5% to 7% weight loss to improve glycemic control, blood pressure and blood lipids; (Level 1a, Grade A,)  reduce the incidence of type 2 diabetes, (Level 1a, Grade A,) microvascular complications (retinopathy, nephropathy, and neuropathy) (Level 1a, Grade B), cardiovascular mortality, and all-cause mortality (Level 1a, Grade B).

6. Adults living with obesity and type 2 diabetes should consider intensive lifestyle interventions that target a 7% to 15% weight loss to increase the remission of type 2 diabetes (Level 1a, Grade A) and reduce the incidence of nephropathy, (Level 1a, Grade A) obstructive sleep apnea (Level 1a, Grade A),  and depression (Level 1a, Grade A).

7. We recommend a non-dieting approach to improve quality of life and psychological outcomes (general well-being, body image perceptions), with mixed results for cardiovascular outcomes (blood lipids, blood pressure), body weight, physical activity, cognitive restraint and eating behaviours. (Level 3, Grade C)

  • Nutrition is important for everyone, regardless of body size or health. Your health is not a number on a scale. When you are ready to make a change, choose behaviour-related goals to improve your nutrition status and health (medical, functional, emotional health) (Table 2).
  • There is no one-size-fits-all healthy eating pattern. Choose an eating pattern that supports your best health and can be maintained over time rather than a short-term diet. Talk to your health care provider to discuss the advantages and disadvantages of different eating patterns to help achieve your health-related goals.
  • How you eat is as important as what and how much you eat. Practice eating mindfully and promote a healthy relationship with food.
  • “Dieting” or severely restricting the amount you eat may cause changes to your body that can lead to weight regain over time.64-66
  • See a registered dietitian for an individualized approach and on-going support for your nutrition and health-related needs.

Medical Nutrition Therapy Author Conflict of Interest Disclosures

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