What a New Study Tells Us About Diet and Weight in Down Syndrome

Last week, a study was published examining the role of diet, nutrition, and physical activity as risk factors for becoming overweight or obese in individuals with Down Syndrome (DS).

The study analysed the diets of 188 people with Down syndrome living in London, Barcelona and Paris (aged 12–45 years, without dementia).

The main finding was that eating higher protein was significantly associated with lower body mass index (BMI). BMI is essentially the measure of body weight relative to height. It is used to determine whether someone is normal weight, overweight or obese. So they found more protein is linked to less weight gain.

As this is an observational study, this finding is interesting, but it is not conclusive, so please don't rush off an buy the next high protein product that is marketed to you in the supermarket as seems to be the case everywhere you look these days!

Why is protein good in Down Syndrome?

The researchers suggested this may be because protein is more filling, helping with appetite regulation. This is particularly important in Down syndrome because appetite regulation seems to be an issue. Research consistently shows that leptin (fullness) signaling is different in DS. This may possibly make them feel hungrier and drive them to overeat junk foods, even when they are not hungry. Anything we can do to tame that appetite and tendency to overeat is a positive in DS.

The study also found that better overall diet quality was linked to a lower BMI. This finding was not hugely surprising. But I suppose for people who still believe it is all about calories it may be a helpful affirmation that food quality really does matter more.

The study also found that the types of fats in the diet correlated to IQ levels.

What do I take away from this?

This study doesn't tell me anything particularly new. Instead it reaffirms my approach to eating in DS.

I tell my clients to lead their meals with protein or always makes sure there is some protein on the plate. Why? Because protein is what we are made of. Protein is the why we eat. Protein is the main driver of appetite. Without protein we would eventually die because our body wouldn't be able to make all the bits and pieces that we need to function on a day to day basis (e.g. blood, bones, skin etc).

Secondly, the study reminded me how important it is to stay on top of the types of fats people with DS are eating. I’d explain more about fats here but it would take all day!

These findings show associations - they are not conclusive

All research has its downsides and this study is not immune. To understand the diets of people with DS, this research used food frequency questionnaires (FFQs) which is fairly standard in nutrition research.

However, even as the standard approach, it is notoriously difficult to capture someone's true diet. A FFQ typically asks something like "how many times a day, on average, did you eat green vegetables over the last year?" This is a hard questions to answer. Did you eat lots in summer, some in winter and none when you were on holiday? Did you start a diet for a few months in January and then stop in February? Hopefully this highlights the difficulty of using FFQs to assess diet. It is a bit of a finger in the air approximation of someone's diet.

Plus it is worth remembering that protein is generally the more expensive part of food and so more likely eaten more frequently by people with higher socioeconomic status. And higher social economic groups are associated with lower BMI. This means the results are likely confounded or a bit distorted. Is the real cause of lower BMI the high protein or the higher social economic grouping that could afford to eat more protein?

So, what does this mean practically?

For me, this study reinforces a simple but powerful framework for eating for people with DS:

• Start meals with a good source of protein (animal or plant-based)

• Focus on nutrient-dense foods rather than calories

• Pay attention to the quality of fats you are eating - more to come from me on this...

It also confirms that protein may be a useful tool in taming that appetite and drive to overeat that seems to affect people with DS.

Reference:

Gomis-González M, Boronat A, Langohr K, et al. Dietary Patterns and Lifestyle Factors as Determinants of Body Mass Index and Body Composition in Individuals with Down Syndrome-A Study Across Three Clinical Sites. Nutrients. 2026;18(5):779. Published 2026 Feb 27. doi:10.3390/nu18050779