Type 2 diabetes and overweight or obesity commonly occur together. In Canada, two-thirds of all adults are overweight or obese, making overweight and obesity the most common chronic conditions in the country.
During diabetes clinic, patients often tell me they want to lose weight. I find it is helpful to first discuss their current weight. The main tool we use for assessing and managing weight is body mass index (BMI), which is calculated using a patient’s height and weight.
Although BMI may over- or under-estimate excess body weight in some circumstances, it is the most widely studied and easily available measure to classify weight. A normal BMI is 18.5 to 24.9 kg/m², overweight is 25 to 29.9 kg/m² and obese is 30 kg/m² or higher. Overweight and obese BMIs are associated with higher risks of certain health conditions, such as high blood pressure, type 2 diabetes and heart disease.
What is a reasonable weight loss goal?
For patients with diabetes who also have overweight or obesity, weight loss improves risk factors for heart disease and may increase lifespan. I find it helpful to discuss with patients their weight loss goals. Studies have shown that as little as 5% weight loss has substantial health benefits, which is often much lower than someone’s own weight loss goal. This means, for example, that someone who weighs 90 kg (almost 200 pounds) would have substantial health benefits by losing 4.5 kg (10 pounds).
Once we have determined that a patient is overweight or obese and established their weight loss goals, the next step is to discuss a strategy for weight loss. The backbone of any weight loss strategy is lifestyle modification, which includes a dietary plan, physical activity and behaviour changes. Let’s discuss each of these components in more detail.
Is there a specific diet to consider?
Several diets are effective for weight loss, including the Dietary Approaches to Stop Hypertension (DASH) diet, the Mediterranean diet, low-carbohydrate diets or low-fat diets. It is important to highlight that no single diet has been shown to work best. Maintaining a diet over the long-term is more important for sustained weight loss than choosing a specific diet, so I recommend choosing dietary changes that fit well with someone’s lifestyle and are sustainable. Often, this means making modest changes over time rather than following extreme and restrictive diets.
Is physical activity important?
Physical activity should include at least 150 minutes per week of moderate physical activity, such as brisk walking. Maintaining physical activity over the long-term is important for achieving and sustaining weight loss, so I encourage patients to choose physical activities that they enjoy.
Weight loss strategies that incorporate behaviour changes are more effective. Behaviour changes can include monitoring food intake and weight, and understanding and overcoming reasons for eating that may be unrelated to hunger. Behavioural goals should be set using the SMART framework, which are goals that are Specific, Measurable, Achievable, Reasonable and Time-specific.
What about medications?
If people with type 2 diabetes do not reach their weight loss goals despite lifestyle modification, then medication therapy can be added. Medications are considered in those with type 2 diabetes with a BMI of at least 27 kg/m² or higher. In Canada, there are currently 3 types of medications approved for weight loss: glucagon-like peptide-1 (GLP-1) receptor agonists, orlistat, and bupropion/naltrexone. Of these, GLP-1 receptor agonists are used most commonly in people with diabetes. In addition to weight loss, these medications lower blood sugars and reduce the risk of heart disease. Although weight loss with GLP-1 receptor agonists varies between individuals, patients may achieve up to 10% to 15% of total body weight. Obesity is a chronic medical condition and therefore, as for other chronic conditions, these medications need to be continued indefinitely for weight loss to be maintained.
Surgery may be considered for some
One final strategy is weight loss surgery, which is typically considered for people with type 2 diabetes and a BMI of 30 kg/m² or higher.
It is important for people with type 2 diabetes who are overweight or obese to discuss their current weight and weight loss goals with their healthcare team. Diet, physical activity and behaviour changes can all be incorporated into your diabetes management plan, to help you achieve sustainable, long-term weight loss. If your weight loss goals are not being met, or if there are other issues (such as prolonged high blood sugars or heart disease), then GLP-1 receptor agonists might also be considered as a component of a weight loss strategy.
