About 2 out of every 5 adults in the U.S. have obesity, while approximately 1 in every 45 U.S. adults has autism spectrum disorder. Due to how common these conditions are, it’s natural for some people to have both, but the reason may not be coincidental. Children and adults with autism are more likely to carry extra body weight. However, research has only shown that these conditions are associated with each other, not that either causes the other.

Understanding the connection between autism and obesity may help you better manage these conditions and improve your overall health.

Obesity and Autism in Adults

Healthcare professionals use a measurement called body mass index (BMI) when diagnosing obesity. The U.S. Centers for Disease Control and Prevention (CDC) states that adults who have a BMI between 25 and 30 are considered overweight, and those with a BMI of 30 or above are considered to have obesity.

It’s important to know that BMI is a calculation based on a person’s height and weight. It does not take into account one’s genetic background, other health conditions, or lifestyle factors such as sleep and stress levels that can influence body weight. It also cannot measure one’s percentage of body fat or the exercise and nutritional habits that are more indicative of long-term health.

Researchers have investigated whether adults with autism spectrum disorder are more likely to have higher BMIs than people in the general population. One study on adults with autism published in Scientific Reports found that 64 percent of male participants and 61 percent of female participants had a BMI of 25 or higher. Another study found that the participants with autism had a higher average BMI than those without autism, although it also found people with autism were more likely to have an underweight BMI than someone without autism.

Obesity and Autism in Children

Several studies have evaluated whether children with autism have a higher risk of obesity than kids in the general population. One analysis of 20 previous studies found that kids with autism were 58 percent more likely to develop obesity than those without autism.

A smaller Dutch study found that preschool-aged kids with autism had obesity rates that were 8 times higher than kids without autism.

How Are Autism and Obesity Related?

There is no evidence that autism causes obesity. However, researchers believe there are a few factors that may cause people with autism to carry excess weight.

Restrictive Eating Habits

While research is limited on the eating habits of adults with autism, studies show that up to 70 percent of kids with autism have atypical behaviors around eating. This can include:

• Selectiveness about what to eat, with a preference for low-nutrition foods
• Food refusal
• Emotional eating
• Food allergies
• Digestive disorders
• Medication side effects that affect appetite

Kids with autism tend to gravitate toward snack foods, sweetened drinks, and higher-calorie options. In addition, children with autism may consume fewer vegetables than kids in the general population.

Both adults and children with autism may also have oral sensory issues. This means they might avoid specific tastes or textures, preferring to eat only foods with a particular mouthfeel. These preferences may be heightened in childhood and relax with age.

Kids, adolescents, and adults with autism might also be more likely to maintain routines when it comes to their food habits, including mealtimes. For example, they may want to eat at a certain time of the day, or eat the same thing repeatedly. Autism can also include differences in executive functioning, which can make it challenging to plan or prepare meals.

Less Physical Activity

Children and adults with autism are less likely to engage in regular physical activity than those in the general population. This may be due to:

• Difficulties with motor skills
• A lack of access to adaptive exercise partners or sports teams
• Challenges connecting socially with others

Getting exercise may also present sensory challenges for some people with autism due to the chaotic nature of gyms or sports fields. Loud noises, bright lights, big crowds, and other sensory stimuli may lead to anxiety. This could prevent them from participating in physical activities. Anxiety is connected to obesity, as well as being linked to autism.

Unconventional Sleep Schedules

Both kids and adults with autism are prone to having difficulty sleeping, as well as sleep disorders. Poor sleep is a risk factor for childhood obesity. Lack of sleep can also lead to an increased risk of obesity in adults.

Poor sleep at night can also make people with autism more tired during the day, making physical activity less appealing.

Medication Side Effects

Certain medications that people take for symptoms of autism may contribute to weight gain. For example, drugs that help reduce irritability, aggression, or moodiness in people with autism can have the side effect of increasing body weight and appetite.

How Can People With Autism Practice Healthy Weight Management?

Your medical team can help you develop healthier habits. You might want to consult a nutritionist, a behavioral therapist, or an occupational therapist. Many people with autism prefer to stick to existing routines, and there are many ways to incorporate movement and healthy eating into one’s daily routine.

• Add more walking to the day — Walk to school, work, or friends’ houses instead of driving.
• Make physical activities a family affair — Ride bikes together or take a family trip to the playground.
• Help children build motor skills — Practice kicking, jumping, catching, and other activities.
• Find the right crowd — Engage in activities that are autism-friendly, ideally led by people with experience in the autism community.
• Build a routine — Make sure physical activity is built into the daily routine so it becomes a habit.
• Choose healthy foods — Limit the amount of unhealthy ingredients in your house. Children can work with a feeding therapist on improving food exposures.
• Redirect attention — If a loved one with autism is prone to overeating, redirect their focus after meals.
• Schedule eating occasions — Add snacks and meals to the daily schedule so they become part of a structured routine.

Caregiver and family involvement can go a long way in building supportive, inclusive routines that make long-term health habits easier for people with autism to maintain. It may help to use visual supports, such as a hunger awareness chart, to help people with autism make healthy food choices and to eat only when they’re hungry. Plan meals and activities that take sensory preferences and sensitivities into account. For instance, to avoid loud noises, try a bike ride on a quiet trail rather than going to a crowded gym.

Speak With Your Doctor

If you have autism or you’re the caregiver for someone with autism, speak with your healthcare provider about healthy weight management strategies. If weight control is a challenge, ask for a referral to an obesity specialist, an autism specialist, or a registered dietitian. They can create a healthy eating and movement plan tailored to your specific needs, interests, and goals.

Talk With Others Who Understand

On MyObesityTeam, the social network for people with obesity and their loved ones, more than 57,000 members come together to ask questions, give advice, and share their stories with others who can relate to their experiences living with obesity.

Are you living with autism and obesity, or do you care for someone who is? Do you have advice for others looking to build healthy habits? Share your experience in the comments below, or start a conversation by posting on your Activities page.