People with Down syndrome are more likely to be obese than their typically developing peers. Sometimes it is the result of untreated hypothyroidism. If there are new symptoms of hypothyroidism, such as increased sleepiness, confusion, or mood changes, then the individual's primary doctor should consider running a blood test to check thyroid function. There is also a suggestion that people with Down syndrome may have a lower level of metabolism, i.e. their bodies may consume less calories and therefore store more.

More generally, though, weight management issues in individuals with Down syndrome are often due to the intake of too many calories in relation to the level of physical activity. Strategies for treating and preventing obesity involve:
 

• Lowering portion sizes
• Emphasizing healthy ingredients that increase bulk (like fiber, fruits and vegetables)
• Making smart choices when it comes to drinks and desserts
• Avoiding snacks
• Empowering adults to monitor their own weight
• Involving supervisors at work and school on the treatment plan
• Preparing lunch at home
• Never using food as a reward
• Introducing a daily exercise routine that is appropriate to the person’s interests and skills

If there is no underlying medical condition contributing to an individual with Down syndrome's weight, then he or she can use the same basic strategies as anyone else would to lose weight: exercise, portion control and healthy food choices.