Jennifer Kuk

Should all people with obesity lose weight?

Jennifer Kuk’s research concentrates on how obesity, diet, and physical activity relate to health. Her current focus is a specific sub-population of people who are obese but who don’t experience the typical health problems we have come to expect with obesity. Sometimes referred to as the “Fit-Fat Paradox”, this intriguing research area has attracted the interest of media outlets across Canada and internationally.


The increasing number of people struggling with obesity has become a large public health problem. Despite the fact that so many people try to lose weight, the percentage of those who successfully lose weight and maintain it long term is less than 5%. Most individuals are not able to manage their weight for the long term; the vast majority are going to struggle with their weight for the rest of their lives unless something changes.

There is a lot of research pointing to the fact that you don’t need to focus on just the scale. Many health markers are easier to improve than body weight, like blood pressure, lipids, stress, and your perspective on life. All these things play into your quality of life, and they might be negatively impacted if you focus too much on your body weight and take severe measures that could be unhealthy, like extreme diets or untested supplements.


Hopefully, our research on physical activity and dietary guidelines will be incorporated in the next version of the Canada Food Guide. Serving sizes have changed over time. My research has shown that people consistently overestimate the size of a serving. People are eating larger portions now than in the 70s, but the food guide serving sizes have not adapted. For example, it says you should have seven servings of grains. Realistically, it’s only three portions for the modern person.


One of the things we try to do is highlight the importance of lifestyle. Physical activity and diet can help improve health outcomes, at any weight.

My biggest contribution is to show that not all fat is the equal in terms of health risk. In particular, we have shown that people with more visceral fat – the fat between your organs – are more likely to die early. Visceral fat is also more strongly related to blood pressure, diabetes, and hypertension risk than subcutaneous fat (the fat that you can pinch under your skin). While the only way to directly measure visceral fat is using magnetic resonance imaging (MRI) or computer tomography (CT), an easy way to estimate it is through waist circumference. Measuring your waist is especially important if you want to monitor changes in your health over time. For example, many people who begin to exercise decrease visceral fat, improve health, and will feel that their pants fit better even though they do not see changes on the scale. Conversely, individuals may stay the same weight over time, but be losing muscle mass and increasing visceral fat mass with age. So health care practitioners should be monitoring your pant size, not just the scale.

What’s Next?

I’m going to continue investigating the “Fit-Fat Paradox” – the small population of people with obesity but with good overall health. Obesity is normally equated with bad health, and it is assumed that everyone who is obese should lose weight. However, it is possible that repeatedly failing to successfully lose weight and keep it off may be worse than just focusing on preventing any more weight gain and having a healthy balanced lifestyle. It is important to consider that there are currently no treatments that consistently return individuals to a normal weight.

Understanding these factors will hopefully help to break down the stigma around obesity. Approximately 80% of patients attending the Wharton Weight Management Clinic report being discriminated against because of their body weight. This is one of the last prejudices deemed acceptable in our society. Individuals with obesity are portrayed as silly, stupid, gluttonous and lazy on TV. Given that body weight goes far beyond simply diet and exercise, this is a clearly unfair generalization.