Research suggests that losing excess weight is one of the best ways to reduce and prevent knee arthritis pain. This is true whether weight loss is achieved through exercise or diet alone. In fact, losing weight is more effective at reducing knee pain than many other commonly used knee arthritis treatments, such as strength training and glucosamine/chondroitin supplements, as well as newer regenerative medicine treatments, such as PRP injections. Many patients can put off the need for knee replacement surgery by losing weight.
Why Is Weight Loss Such an Effective Treatment?
Weight loss takes pressure off arthritic knee joints. Losing weight reduces friction between the bottom of the femur (thigh bone) and top of the tibia (shin bone), where protective knee cartilage has been damaged or worn away. Losing weight also puts less strain on the knee’s soft tissues, including ligaments and tendons.
Compressive Load on the Knee: The Compounding Effect of Extra Weight
The pressure on a knee joint at any given time is referred to as the “compressive load” on the knee. The compressive load changes according to activity. For example, compressive load on the knees when—
Lying down is 0 lbs
Standing upright is equal to a person’s body weight
Walking is estimated to be 3 times a person’s body weight
In other words, experts estimate that when a foot hits the ground during walking, the knee experiences 3 lbs of pressure for every 1 lb of body weight. This means a person who weighs 150 lbs may feel 450 lbs of pressure in a knee during one stride.
Losing a few pounds can make a big difference over time
Reducing the compressive load on the knees can make a significant difference when added up over many steps.
To illustrate this point, below are compressive load calculations for a person who is 5’4” and walks one mile, requiring about 2,300 steps.4 In the first set of calculations, the person weighs 150 lbs; in the second set of calculations, the person weighs 140 lbs.
(150 lbs x 3) x (2,300 strides per mile) = 1,035,000 lbs in compressive load per mile (517,500 lbs per knee)
(140 lbs x 3) x (2,300 strides per mile) = 966,000 lbs in compressive load per mile (483,000 lbs per knee)
By losing 10 pounds, the person in this example can reduce the cumulative compressive load on his or her knees by 69,000 lbs, a 6.7% difference. Added up over days, months, and years of walking, losing 10 lbs can be quite significant in easing knee pain as well as reducing wear and tear on the knees.
Variations in compressive load
Many experts estimate that during one walking stride the knee experiences 3 lbs of pressure for every pound of body weight, but others estimate anywhere between 2 lbs to 7 lbs of pressure for every pound of body weight. The exact figure can vary depending on body mechanics, walking surface, and other factors. Ultimately, experts agree that the compressive load on knees (and hips, and ankles) is a multiple of body weight, and that losing excess weight can play a significant role in reducing knee pain.
Tips for Losing Weight to Treat Knee Pain
Weight loss is a proven treatment for arthritic knee pain, but few people use it. Losing excess pounds can seem like a big challenge. Below are a few ideas for successfully achieving and maintaining weight loss. Incorporating just one or two of these ideas into a daily routine may produce notable weight loss.
1. Eliminate One Bad Habit
Removing one fattening or sugary item from a daily diet can make a big difference over time. For example, a person can trade in a morning muffin for a piece of fruit or swap out sweetened beverages for water.
2. Make Meals from Scratch
By making meals from scratch, people can avoid most trans fats as well as unnecessary sugar, additives, and preservatives, which many processed foods contain. Research suggests that additives and preservatives are associated with inflammation and obesity.
3. Eat More Fiber Every Day
Increasing fiber intake is often recommended for losing weight. Eating high-fiber foods can make a person feel full, thereby decreasing the cravings for high-caloric foods. Why?
Fibrous foods take up more space with fewer calories. A candy bar or sugary granola bar can be 180 to 300 calories. A cup of uncooked leafy greens has less than 10 calories. A large vegetable salad can be filling and less than 100 calories. (Keep in mind that adding bacon bits, croutons, candied nuts, and heavy dressings can add several hundred calories.)
Fibrous foods take longer to digest. Digestion times vary from person to person, but in general, fibrous foods such as fruits and vegetables take longer to break down in the stomach and large intestine, leaving people feeling full long after they have eaten. Candy and baked goods, such as crackers and cookies, are digested quickly, so people feel hungry again sooner.
Leafy greens are not the only high-fiber foods. Other vegetables, fruits, beans, rolled oats and many other foods are high in fiber.
4. Burn a Few More Calories Each Day
While reducing calorie intake is the most reliable way to lose weight, burning calories can also help shed pounds. Hitting the gym, swimming, and doing water aerobics are tried-and-true ways to burn calories, but there are other ways to expend energy. Going for a walk each day, gardening, or doing gentle yoga and stretching on the living room floor will burn more calories than sitting still.
5. Do Not Eat Before Bed
Putting an end to after-dinner snacks and late-night eating habits is an easy way to drop pounds. Not only does this approach cut out unnecessary calories, it helps the body digest and metabolize food; the body’s digestive and metabolic systems work most efficiently during the day.
A physician or registered dietician can work with patients to discuss the above ideas for weight loss as well as other ideas.
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