Weight, appetite and autism or ADHD: what the research shows

Parents of autistic children and children with ADHD (attention deficit hyperactivity disorder) often ask about weight. Some worry that their child eats too little or too narrow a range of foods. Others worry that their child's weight is climbing. Sometimes both are true for the same child. This note sets out what the research shows, how sure we can be, and what to ask your doctor.

Most of the numbers below come from studies in the United States. There is little data from the UK. We do not know how closely the US figures apply to children here.

What the studies show: autism

Several reviews have pooled studies that compare autistic children with other children.

• A 2022 review of 20 studies found that about 17 in 100 autistic children and teenagers were living with obesity. Autistic children were about 1.6 times as likely to have obesity as children in the comparison groups. All but three of the 20 studies were from the US (Sammels and colleagues, 2022).
• A 2019 review put the figure at about 22 in 100, with a 41% higher risk than other children. The link was stronger in older children, in girls, and in studies from the US (Kahathuduwa and colleagues, 2019).
• A 2020 review of 95 studies of autism and ADHD across all ages found that the share of autistic people living with obesity rose with age, from about 17 in 100 at age 2 to 5 years to about 31 in 100 in adults (Li and colleagues, 2020).

The few European studies in the 2022 review did not find a clear difference between autistic and non-autistic children (Sammels and colleagues, 2022).

What the studies show: ADHD

• A 2016 review of 42 studies found obesity in about 10 in 100 children with ADHD, compared with about 7 in 100 children without ADHD. People taking ADHD medicine were not at higher risk (Cortese and colleagues, 2016).
• Another 2016 review found a small link overall. The authors judged it likely to be of no clinical importance in younger children, possibly important in teenage girls who also had other conditions, and important by adulthood (Nigg and colleagues, 2016).

How big is the link?

The link between autism or ADHD and higher weight is consistent across reviews, but in children it is modest. In the ADHD figures above, the difference is about 3 extra children in every 100. The link gets stronger in the teenage years and in adults. Most autistic children and children with ADHD are not living with obesity.

These studies show a link. They do not show that autism or ADHD causes weight gain. Many other things affect weight, including family income, sleep, activity and medicines, and studies cannot always separate them.

Why weight can change

Medicines

Some medicines raise appetite and weight. In trials in children and teenagers, risperidone led to an average weight gain of about 1.8 kg more than placebo (a dummy tablet). Olanzapine led to about 3.5 kg more and aripiprazole to about 0.9 kg more (Almandil and colleagues, 2013).

Stimulant medicines for ADHD, such as methylphenidate, often reduce appetite during the day. NICE (the National Institute for Health and Care Excellence) asks doctors to check height and weight regularly in children taking ADHD medicine. If weight loss is a concern, the options it lists include taking the medicine with or after food, and adding a meal or snack early in the morning or late in the evening when the medicine has worn off (NICE NG87, 1.8.5 and 1.8.6).

Do not stop or change any medicine because of weight or appetite without talking to the doctor who prescribes it.

A narrow range of foods

Many autistic children eat a small range of "safe" foods, often because of taste, texture or smell. This makes the diet less varied. It does not always mean low weight. If the safe foods are filling, high-energy foods, a child can gain weight while still missing out on some vitamins and minerals.

Sleep

Sleep problems are common in autistic children and children with ADHD. NICE advises explaining to families that lack of sleep may increase the risk of excess weight gain in children and young people (NICE NG246).

Activity and screens

Team sports and busy play areas can be hard for some autistic children and children with ADHD, and screen time may be higher. These may play a part, but there is little good research on them in these groups.

Higher weight does not rule out ARFID

ARFID (avoidant/restrictive food intake disorder) is an eating disorder where a child avoids or restricts food because of the sensory qualities of food, fear of choking or being sick, or little interest in eating. It is not about body shape or wanting to be thin. ARFID is diagnosed by the eating pattern and its effects, such as missing nutrients, needing supplements, or meals causing major problems in daily life. Low weight is one possible effect, not a requirement.

A child at an average or higher weight can still have ARFID. Advice to cut down on food can be risky for a child with restrictive eating. If your child eats a very narrow diet, speak to your GP or paediatrician before making changes, and ask whether a dietitian should be involved. For more, see Nutritional Issues in Autistic Children: A Practical Guide for Parents and Paediatricians.

What helps

The evidence on weight support for autistic children is thin. A 2019 review found 12 studies. Half showed a clear drop in weight, but 8 of the 12 were of weak quality. The most promising programmes were tailored to the child, covered several areas at once, and were run by a team of professionals (Healy and colleagues, 2019). We found no strong trials of weight support for children with ADHD.

NICE guidance on overweight and obesity asks health professionals to ask the family and the child for permission before discussing weight or taking measurements (NICE NG246, 1.10.3).

Practical steps that suit most families:

• Keep your child's safe foods available. Offer new foods alongside them, in small amounts, without pressure.
• Avoid calling foods "good" or "bad".
• Keep regular meals and snacks at the same times each day.
• Find movement your child enjoys and can manage, such as walking, swimming, trampolining or a favourite game.
• Protect sleep. See Sleep problems in autistic children: what helps.
• Talk about health, energy and feeling well, not about weight, in front of your child.

When to get help

Speak to your GP, paediatrician or the doctor who prescribes your child's medicine if:

• your child's weight or height is moving across the lines on their growth chart in the red book (Personal Child Health Record), up or down
• your child eats a very small range of foods, or the range is getting smaller
• your child is often tired, pale or unwell, or has problems with bowels or teeth linked to diet
• mealtimes cause a lot of distress
• a new medicine has changed your child's appetite or weight a lot

References

1. Sammels O, Karjalainen L, Dahlgren J, Wentz E. Autism spectrum disorder and obesity in children: a systematic review and meta-analysis. Obesity Facts. 2022;15(3):305–320. doi:10.1159/000523943
2. Kahathuduwa CN, West BD, Blume J, et al. The risk of overweight and obesity in children with autism spectrum disorders: a systematic review and meta-analysis. Obesity Reviews. 2019;20(12):1667–1679. doi:10.1111/obr.12933
3. Li YJ, Xie XN, Lei X, Li YM, Lei X. Global prevalence of obesity, overweight and underweight in children, adolescents and adults with autism spectrum disorder, attention-deficit hyperactivity disorder: a systematic review and meta-analysis. Obesity Reviews. 2020;21(12):e13123. doi:10.1111/obr.13123
4. Cortese S, Moreira-Maia CR, St Fleur D, et al. Association between ADHD and obesity: a systematic review and meta-analysis. American Journal of Psychiatry. 2016;173(1):34–43. doi:10.1176/appi.ajp.2015.15020266
5. Nigg JT, Johnstone JM, Musser ED, et al. Attention-deficit/hyperactivity disorder (ADHD) and being overweight/obesity: new data and meta-analysis. Clinical Psychology Review. 2016;43:67–79. doi:10.1016/j.cpr.2015.11.005
6. Almandil NB, Liu Y, Murray ML, et al. Weight gain and other metabolic adverse effects associated with atypical antipsychotic treatment of children and adolescents: a systematic review and meta-analysis. Paediatric Drugs. 2013;15(2):139–150. doi:10.1007/s40272-013-0016-6
7. Healy S, Pacanowski CR, Williams E. Weight management interventions for youth with autism spectrum disorder: a systematic review. International Journal of Obesity. 2019;43(1):1–12. doi:10.1038/s41366-018-0233-8
8. National Institute for Health and Care Excellence. Attention deficit hyperactivity disorder: diagnosis and management (NG87). 2018, updated 2019. nice.org.uk/guidance/ng87
9. National Institute for Health and Care Excellence. Overweight and obesity management (NG246). 2025. nice.org.uk/guidance/ng246

Dr Odet Aszkenasy is a Consultant Community Paediatrician and the author of The Genetics of Autism: A Guide for Parents and Professionals.