The Mechanics: Every Pound Counts Fourfold
Walking on level ground puts roughly four times your body weight through each knee with every step, and up to six times when going downstairs. Losing 5 kg therefore takes 20-30 kg of repetitive load off the joint with every step you take. This is why even modest weight loss produces large symptom changes in knee and hip OA.
Beyond Mechanics: Inflammation
Fat tissue, particularly around the abdomen, is metabolically active and releases inflammatory cytokines that travel through the bloodstream to joints throughout the body. This explains why weight loss also improves symptoms in hand OA, where mechanical load is unaffected. C-reactive protein and IL-6 levels fall measurably within weeks of starting weight loss.
The 5-10% Threshold
Trial evidence consistently shows that losing 5% of body weight gives measurable benefit, 10% gives substantial benefit, and combining weight loss with exercise is more effective than either alone. For an 85 kg person that is 4-8 kg — an achievable target over six to twelve months.
What to Eat
Mediterranean-style eating — vegetables, legumes, whole grains, oily fish, nuts, olive oil, modest dairy, minimal ultra-processed food — produces sustainable loss without calorie counting and reduces inflammation independently. Our arthritis nutrition guide and foods to avoid page have practical meal templates. Crash diets fail and accelerate muscle loss.
Movement That Works With Painful Joints
Pool exercise, stationary cycling, recumbent bikes and chair-based strength work all burn calories without stressing knees and hips. Start with 10 minutes most days and build. Combining cardio with twice-weekly resistance work preserves muscle, which is the main determinant of long-term function.
Sleep, Stress and Sustainable Habits
Poor sleep raises ghrelin (hunger hormone) and lowers leptin (fullness hormone), making weight loss harder. Stress drives emotional eating. Address both alongside diet — they are not separate problems.
When to Seek Specialist Support
If BMI is above 35 with significant joint pain, ask your GP about Tier 3 weight-management services, GLP-1 medication, or bariatric surgery. These options now sit firmly within mainstream arthritis care, not as a last resort.