The paradox of weight loss: why losing pounds may not always lead to better health
One of the lasting memories from my teenage years is what I now recognise as an obsession with weight control. Thin was in, and magazines promoted a variety of diets, each claiming effectiveness, often accompanied by images of beautiful, slim models. Not much has changed.
Diets, intermittent fasting, weight-loss surgery, and more recently, weight-loss injections continue to be marketed as solutions for shedding pounds. Achieving a healthy weight is widely regarded as essential for overall wellbeing.
Many studies have explored the relationship between weight changes and mortality, as well as mortality in obese people with heart disease. These studies often suggest that excessive weight is unhealthy and that people with obesity and heart disease should lose weight.
However, findings from a recent study, of which I was a co-author, challenge this assumption. Our research indicates that significant weight loss – greater than 10kg – can actually increase the risk of early death in obese people with cardiovascular disease.
This study was based on data from over 8,000 participants in the UK Biobank, a comprehensive resource for medical research that includes genetic data.
While it’s known that rapid weight loss can signal underlying health issues and lead to serious complications, the weight changes in our study were observed over an average of nine years, meaning for some participants, these changes were relatively quick.
This creates a paradox. While both obesity and cardiovascular disease are known to increase the risk of early death, in obese people with cardiovascular disease, weight loss – intended to improve health – can have the opposite effect.
The relationship between body weight and illness is complex. Though obesity contributes to cardiovascular problems, studies have also shown an increased risk of early death in those with chronic heart failure who are lean, and in people with coronary artery disease whose weight fluctuates.
Obesity rates are rising, but simply focusing on weight loss may not be the answer.
Variability in weight loss
For weight loss to be effective, we must consider the diverse factors contributing to weight gain, which vary from person to person. Genetics play a significant role in appetite and metabolism, and they can also influence lifestyle factors like overeating, inadequate exercise and poor dietary choices that lead to obesity.
In our study, my colleagues and I couldn’t account for all the factors behind the participants’ obesity or the methods they used to lose weight. This means we can’t definitively determine which weight-loss strategies – whether in terms of duration, diet or physical activity – pose the greatest risks.
The conventional approach to healthy weight – using body mass index (BMI) – may not apply to everyone. BMI is increasingly recognised as having limitations. Some people may tolerate higher weights without adverse health effects. The real question isn’t how quickly weight should be lost, but how quickly it should be lost for each person.
Given the current evidence, we cannot accurately determine an ideal weight range that’s universally beneficial for health. However, intriguing patterns are emerging from various countries.
For instance, Tonga has a high rate of obesity, yet it experiences significantly lower rates of heart-disease-related deaths than many European countries where obesity is less prevalent. Tonga also reports lower levels of alcohol consumption and suicide than most European nations.
Health encompasses both physical and mental wellbeing. Shifting the focus to holistic wellbeing and happiness may offer more lasting health benefits. Treating obesity requires a comprehensive approach, addressing all underlying factors contributing to the condition.
Barbara Pierscionek does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.