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Body Weight and Knee Pain

Reviewed by Michael W. Smith, MD on September 01, 2020

Your knees are powerhouses. They’re the biggest, strongest, joints in your body, and most people use them throughout the day to sit, stand, walk, jump, and bend. They bear 80% of your body weight when you stand still and 150% or more when you walk across the room. In a 160-pound person, that’s 240 pounds of force!

How Does Weight Affect Your Knees?

More weight puts more strain on joints and on the cartilage that protects the ends of your bones. Extra body fat also sometimes increases chemicals in your blood that inflame your joints.

Both these things can lead to osteoarthritis (OA). In this condition the smooth, slippery cartilage that covers the ends of bones in a joint slowly wears away. Instead of gliding over one another, your bones rub against one another.

Symptoms like pain, swelling, stiffness, and loss of motion often get worse over time.

Normal wear and tear is another leading cause of osteoarthritis, especially after age 50. Extra body weight can also cause OA or make it worse if you already have it.

In addition, extra body fat, especially around your belly, often leads to gout. The fat triggers your body to stop responding to the hormone insulin, a condition known as insulin resistance. This makes it harder for your kidneys to get rid of uric acid. It builds up in your joints and forms crystals that cause painful attacks. Gout most often affects your big toe or ankle, but it can show up in your knees, too.

What Helps: Maintain a Healthy Weight

Weight loss can really help your knees. Drop 10 pounds, and you’ll take as much as 40 pounds of force off them, depending on what you’re doing.

Losing even a small amount can help. And the earlier you do it, the better. Keep the weight off, and you won’t be as likely to get arthritis later in life.

It isn’t just the weight. Fewer fat cells might mean fewer hormones to inflame your knees and other joints. This makes gout less likely by lowering levels of uric acid in your body. It’s especially helpful if you do it with good diet and exercise habits.

Talk to your doctor about your ideal body mass index, a measure of body fat based on height and weight.

What Helps: Diet

Changing your diet will help you lose weight, but eating better food can have other benefits, too.

Healthy eating lessens the inflammation that sometimes causes joint pain. In particular, fatty fish like salmon, tuna, mackerel, and herring are rich in omega-3 fatty acids and are good for this, along with nuts, tomatoes, olive oil, and green leafy vegetables.

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It isn’t always easy to put this into a daily diet that works for both weight and general good health. Your doctor or dietitian can work with you to build a plan with the right mix of exercise and diet changes. Or you could try the National Institute of Health’s Body Weight Planner tool, which gives you a meal plan based on your activity level and weight loss goals.

In general, aim for a healthy, balanced diet that you can stick with even after you lose weight. Nuts, beans, eggs, skinless chicken, lean meat trimmed of visible fat, and fish are good proteins. Cover at least half your plate with fresh vegetables, fruits, and whole grains like oatmeal, brown rice, or whole-grain bread.

What Helps: Exercise

Exercise that leads to weight loss will help take pressure off your knees. But it, too, has other benefits.

It might lessen chronic inflammation and can strengthen and stretch the complex collection of muscles, ligaments, and tendons that move the knee joint.

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Movement keeps your cartilage healthy, too. In fact, people unable to move because of surgery, injury, or illness actually start to lose cartilage in their knees from lack of use.

It’s a good idea to try to mix up your exercise types:

  • Aerobic exercise, like walking, swimming, or rowing, could lessen inflammation and increase your stamina. That allows you to remain active for longer periods.
  • Resistance exercise, like weightlifting or lunges, strengthens and stabilizes muscles around the knee joint, like your hamstrings, calf muscles, and quadriceps.
  • Stretching muscles and connective tissue around your knee helps increase your range of motion, or the distance you can move a joint.

Just make sure you start slow, warm up, and learn the correct technique for any exercise that you do. Talk to your doctor if you already have knee pain so you don’t choose an activity that makes it worse. It may be better to avoid exercise that involves kneeling, bending deeply, or running downhill, which could be especially hard on your knees.

WebMD Medical Reference

Sources

SOURCES:

American Academy of Orthopaedic Surgeons: “Arthritis of the Knee,” “Safe Exercise.”

American Council on Exercise: “What exercises are best to strengthen my knees?”

Harvard Health Publishing: “10 tips to prevent injuries when you exercise,” “Age-proof your knees,” “Foods that fight inflammation,” “Why weight matters when it comes to joint pain.”

Johns Hopkins Medicine: “Role of Body Weight in Osteoarthritis.”

Arthritis Foundation: “Anatomy of Arthritis Pain,” “Benefits of Exercise for Osteoarthritis,” “Benefits of Weight Loss,” “Exercising With Osteoarthritis,” “Gout,” “How Fat Affects Gout,” “Osteoarthritis.”

National Institute of Diabetes and Digestive and Kidney Diseases: “Body Weight Planner Tool,” “Health Risks of Being Overweight.”

Current Opinion in Endocrinology, Diabetes and Obesity: “What causes the insulin resistance underlying obesity?”

Journal of Lifestyle Medicine: “Hyperuricemia as a Potential Determinant of Metabolic Syndrome.”

Rush University Medical Center: “5 Tips for Preventing Knee Pain.”

Beaumont Health: “What to Ask Your Doctor About Weight Loss.”

National Institutes of Health: “Online Weight Management Gets Personal.”

National Heart, Lung, and Blood Institute: “Calculate Your Body Mass Index.”

CDC: “Healthy Eating for a Healthy Weight.”

UC San Diego Health: “Exercise … it Does a Body Good: 20 Minutes Can Act as Anti-Inflammatory.”

Journal of Anatomy: ”Exercise and osteoarthritis,” “The effects of exercise on human articular cartilage.”

Stop Sports Injuries: “Overuse Injury.”

Mayo Clinic: “Overuse injury: How to prevent training injuries,” “Yoga: Fight stress and find serenity.”

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