Most Americans pack on the pounds in middle age. In fact, it’s such a suburban rite of passage that we have cute little names like “love handles” and “muffin top”. While most would understand that gaining weight puts more pressure on your knees and that this could lead to more wear and tear, most don’t know that the metabolic changes that happen with weight gain also degrades cartilage, a phenomenon sometimes referred to as weight gain knee arthritis. Now a recent study shows just how devastating those few extra inches are to your knees.
More weight obviously means more pressure on joints which leads to more wear and tear. However, what most people don’t understand is that it’s the metabolic changes that go with that weight gain that really chew up your cartilage. For example, the reason why most of us gain weight in middle age is because of changes in hormone and growth factor levels that reduce our ability to maintain tight blood sugar control. So when you’re 20 and you scarf down that double crust pizza, your body releases just the right amount of insulin to move all of those carbs into energy. When you’re 40 and you down that same pizza, most of us release way too much insulin which then makes us more hungry and triggers our body to turn that crust into fat. What you likely didn’t know is that this huge burst of insulin also wrecks your knees independent of any extra mechanical pressure from extra weight.
The new study looked at just how these middle aged extra pounds impact the knees by using data from an existing arthritis surveillance study. For patients that gained just 5% more weight over a four year period after age 45 the odds of cartilage breakdown in the knee increased more then 11 times! The meniscus was also more then 4 times more likely to look worse! How much is 5%? Well if you’re male and weigh 170 pounds at age 45 and gain just 9 pounds in 4 years, you would fit the criteria in this study. If you’re female and weigh 120 pounds, a 6+ pound weight gain would apply!
The upshot? It doesn’t take much weight gain in middle age to wreck your knees. This damage isn’t likely happening because of wear and tear due to extra mechanical pressure, but more likely the result of the poor blood sugar control that caused the extra weight gain in the first place!