When you're dieting, you may think of your hips, waist and thighs shrinking, but your feet may get smaller when you lose weight too. Depending on how much weight you shed, you may need to invest in smaller shoes along with new clothes.
Losing weight can also affect your feet in other ways. Read on for the details on how weight loss might change your shoe size and foot health.
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Shoe Size After Weight Loss
Many people will notice some extra room in their shoes after losing a significant amount of weight. Yes, your feet can "shrink" — but probably not in the way you think.
When someone is carrying extra weight, the tendons and ligaments in their feet often stretch, says obesity medicine physician Fatima Cody Stanford, MD, MPH. "When a person loses weight, there is a reduction in that stretch, which leads to potential changes in shoe size," Dr. Stanford says. "Also, there may be a decrease in the amount of soft tissue."
A March 2018 study in Homo looked at the effect of obesity on foot arch heights in 270 people assigned female at birth between ages 10 and 84. Flat feet were mostly found in those who were older and those with obesity, but the authors concluded that a high BMI contributes to the development of flat feet more than age.
In other words, your shoe size may change when you lose weight, but it's not necessarily because you're losing weight or fat in your feet.
But Can Your Foot Actually Shrink?
Yes, but your bones don't budge.
"When our body loses weight, yes, our feet can lose fat also," says physical therapist Karen Joubert, PT, DPT. "Your actual structure in the feet — which begins with the skeletal bones — remains the same. What you will notice, however, is that the feet are less swollen due to a reduction in overall body fat and perhaps decreased inflammation. This will create the sensation of your feet 'shrinking.'"
How Weight Loss Affects Your Feet
When you carry a lot of extra weight, your feet can suffer. Over time, that extra weight stretches out connective tissue, your foot muscles strain to support you and natural fat pads that cushion the soles of your feet wear down. You also might experience plantar fasciitis, a painful inflammation of the tissue on the bottom of your foot, as well as ankle pain, according to the Cleveland Clinic.
"Did you realize that every little step you take loads your feet with over 120 percent of your body weight?" Joubert says. "Rule of thumb is the load force increases roughly 4 to 5 pounds with every extra pound of excess weight for your recommended size and body weight."
You can use that math to determine how much pressure is taken off your feet when you lose weight. If you lose 10 pounds, for example, you're removing about 50 pounds of pressure from your feet.
With this pressure reduction, there's an improvement in motion of the foot, Dr. Stanford says, and it reduces the amount of force you use to strike the ground.
Can Pregnancy Affect Foot Size?
Yep! A small March 2013 study in the American Journal of Physical Medicine & Rehabilitation studied foot changes in a group of people throughout their pregnancies. The authors concluded that pregnancy is associated with a decrease of arch height and rigidity, and greater foot lengthening, all of which causes you to need a bigger shoe size.
These changes in the feet could actually be permanent, contributing to the increased risk for musculoskeletal disorders.
"We know that pregnancy is often associated with major shifts of weight and changes in hormones, which can relax the ligaments and joints in the foot as well as the rest of the body," Dr. Stanford says. "The key hormonal change that affects the foot is a rise in progesterone. In the first trimester, we also see high levels of relaxin, which also can loosen the ligaments."
To help with these issues, pregnant people should try to avoid standing for long periods, sleep on their left sides, wear compression stockings, get some exercise every day and wear loose, comfortable clothing and socks, per the Mayo Clinic.
- Fatima Cody Stanford, MD, MPH, MPA, MBA, FAAP, FACP, FAHA, FAMWA, FTOS
- Homo: "Foot Longitudinal Arches in Obese, Overweight and Normal Weight Females Who Differ in Age"
- Cleveland Clinic: "Shoes Getting Tight? Why Your Feet Change Size Over Time"
- Karen Joubert, PT, DPT
- American Journal of Physical Medicine & Rehabilitation: "Pregnancy Leads to Lasting Changes in Foot Structure"
- Mayo Clinic: "What Causes Ankle Swelling During Pregnancy, and What Can I Do About It?