I am considering having liposuction to address my long-term weight problem: I have always wanted to be thinner, not just to look better but to be healthier, too. Will this help?

Plastic surgery cannot be a replacement for investing in physical activity to improve your health. While liposuction may make people look leaner, a recent study indicates it won't necessarily improve health issues related to obesity. The study evaluated 15 obese women before and 10-12 weeks after abdominal liposuction, assessing insulin sensitivity as well as other risk factors for coronary heart disease. While the women were thinner, the procedure did not significantly improve the abnormalities associated with being obese.

So while liposuction may decrease your bottom size, sensible weight loss is better for your health. If plastic surgery is going to provide you with the catalyst to help you, be honest with yourself, embrace it, but don't be naive enough to feel it can replace the physical investment you can make for your own health.

The USA National Weight Control Registry lists 4,000 participants who have all lost 50lb and kept it off for an average of five years. They have no special secrets but they do all share four common characteristics: they consume a moderately low number of calories (1,300-1,500 a day, of which 23% to 24% come from fat), eat breakfast almost every day, monitor weight frequently for early warning signs ofweight gain and, above all, participate in a high level of physical activity for approximately 60-90 minutes a day, walking being the most popular.

· Joanna Hall is a fitness expert (joannahall.com). Send your exercise questions to Weekend, 119 Farringdon Road, London EC1R 3ER. Email weekend@theguardian.com