The prevalence of obesity in individuals with PWS varies by age groups, although it has been shown to have a prevalence of 40% in children and adolescents. As individuals with PWS enter adulthood, the prevalence of obesity increases to 82% – 98%, depending on the study group. It is well accepted that once excessive weight gain and hyperphagia begin, caloric intake must be significantly restricted to prevent obesity. However, experienced researchers and clinicians recognize that significant calorie restriction subsequently increases the hunger drive and behavioural problems even more. Thus, many research groups have sought to identify the optimal diet for individuals with PWS to maintain weight control, especially once the hyperphagia drive has developed.

Currently, the most utilized/recommended dietary intervention to prevent worsening obesity in adolescents with PWS is calorie restriction. Studies evaluating optimal calorie restriction in individuals with PWS have shown that a diet consisting of 8–11 kcal/cm height helps maintain body weight in a healthy range. Around 2 years of age, when children with PWS enter nutritional phase 2a they can gain excessive weight, even without a change in appetite or intake. It has been demonstrated, in a long-term natural history study of individuals with PWS, that a well-balanced, energy-restricted diet (~30% fat, 45% carbohydrates, and 25% protein, and at least 20 g of fiber per day) limits weight gain and reduces excess fat mass.

Although there have been no long-term studies done to investigate this issue in PWS, several studies in healthy individuals have demonstrated that non-nutritive sweeteners have a negative impact on the intestinal microbiome, as well as weight control. Low-calorie sweeteners disrupt the composition and function of the gut mucosa and microbiome. Several large-scale prospective cohort studies found positive correlation between non-nutritive sweetener use and long-term weight gain. Humans generally will seek to fulfill an innate craving for sweetness, even in the absence of hunger. This drive is compounded in individuals with PWS. Non-nutritive sweeteners activate hedonic response to sweetness and lead to increased appetite. Non-nutritive sweeteners, precisely because they are sweet, encourage increased craving and dependence for sweet taste. Repeated exposure trains flavor preference. There is a strong correlation between a person’s customary intake of a flavor and preference for that flavor. It is theorized that the regular use of non -nutritive sweeteners in a PWS person’s diet will likely further increase hyperphagia and food seeking.

Upon review of all of the available evidence, it seems that the best diet for adolescents with PWS is most similar to the Mediterranean diet. The nutritional profile of the Mediterranean diet is largely plant-based, rich in complex carbohydrates, vegetables, fruits, legumes and nuts, in addition to abundant fish intake (including oily fish). The Mediterranean diet encourages moderate consumption of animal-derived proteins, including eggs, poultry, and dairy products and low consumption of red meat, processed meats and sweets. Moreover, the Mediterranean diet is a healthy diet for everyone, so if the whole family eats the same foods, there is improved adherence for the individual with PWS over the long term. Additionally, this diet is easier for families to adhere to long term compared to other hypocaloric diets used for weight management in PWS, mainly due to variety of foods and flavors, higher content of fiber and healthy fat to improve feelings of satiety, and liberal use of vegetables to provide more volume to meals.

Dietary Management for Adolescents with Prader–Willi Syndrome – Jennifer L Miller and Michael Tan

The above article was written by Clem’s specialist, Dr. Miller and her colleague Mike Tan, who is a nutritionist and works with her in the Pediatric Endocrinology Department at UF. They have developed these dietary guidelines based on their extensive experience with PWS individuals over a considerable period of time. We are so very fortunate to have been able to work closely with them as we guide Clem through her childhood and establish her dietary habits.

Upon learning of Clem’s PWS diagnosis, we knew that she would require a restricted and closely monitored diet. When she was diagnosed with T1D at 18 months, this took on an additional layer of significance. Now food choices wouldn’t only affect her in the long run (obesity and hyperphagia), but would also affect her in real time (hypo/hyper glycemia, insulin requirements, insulin resistance). So, with the guidance of Dr. Miller and Mike Tan, we set out to craft a diet for Clem that would keep her healthy, supply the necessary nutrition for growth without obesity, control her blood sugar levels and attempt to moderate any sugar cravings that could lead to increased levels of hyperphagia. It was a tall order but absolutely necessary.

As Clementine has grown and started to move through the nutritional phases of PWS, we have adjusted her diet in regard to portion sizes, but the overall rules for food choice remain the same. We do not count calories (but we will if we ever need to make weight loss a goal). We try to incorporate the principles of the Mediterranean diet into most of our meals. We avoid processed foods. We avoid added sugars and artificial sweeteners. The general rule of thumb is if it tastes sweet, it shouldn’t be included in her diet. We do count carbohydrates (mostly because of the T1D) and we usually max out at a daily total of between 100 to 115 grams of carbs a day. Just as a reference point, a can of soda had roughly 39 grams of carbs. We try to make sure that everything she eats has nutritive value and isn’t just empty calories. There are times when she is offered a special treat but we limit the frequency of these occasions. Usually these treats are healthier, modified versions of typical treats. Think keto ice cream for example.

Because we have been very diligent about Clem’s diet and also because we incorporate daily exercise into her routine, she has never been overweight. It’s also fair to mention that she has good genes on her side! My husband’s family are all naturally thin people. My side of the family is also normal weight but it takes considerably more effort!

We took her to the orthopedist on Tuesday and they took very detailed and accurate body measurements. Clem is 4’6″ (137 cm) tall and weighs 69# (31.3 kg). This puts her in the 47th % for her age with a BMI of 17. It’s just about where she needs to be. We closely monitor her weight because it can start to increase rapidly. We don’t want to find ourselves in a situation that would require she lose weight. That can be a difficult process for anyone, much less a child her age.

It’s easy to maintain her diet when we are at home. But out in the real world, it is MUCH more difficult. Food is everywhere and bad food represents a large part of the typical American diet. We seldom eat out because it’s simply too hard to be certain of the ingredients and also the carb counts (for proper insulin dosing). That means I cook almost every meal every day. Suffice it to say I’ve grown to detest cooking and meal planning. We all eat the same dinner. On a positive note, Clem’s diet necessities have meant that the rest of us have vastly improved our own diet and health.

Clem has never eaten things like baked goods or candy. Soda and fruit juice are off limits. Prepackaged foods are usually a no go. Almost all drinks are on the “do not consume” list. Clem’s beverage choices are limited to plain water (which she hates), unsweetened almond milk, unsweetened banana milk and coffee. It’s hard! But I do think there is some truth to the saying “you don’t miss what you never had”. Because we have been following this style of eating since Clem was born, she knows no other way!

Clem understands, as best as she is capable, that she has a difference in her body that makes it impossible for her to eat a lot of typical foods. She is used to it but that doesn’t mean she is immune to the unfairness of it or that she doesn’t want to eat the things she sees others eating. Every child wants to be the “same” as their peers.

But as with all other challenges, Clem accepts what is, improves what can be improved and takes the joy of whatever is offered. We can all learn a lesson from her.