BARDET-BIEDL SYNDROME (BBS)

Bardet-Biedl (pronounced BAR-day BEED-el) syndrome, also known as BBS, is a rare genetic disease of obesity. BBS has a wide range of symptoms, including early-onset obesity and hyperphagia (hai-pr-fay-jee-uh). Hyperphagia is insatiable hunger, also described as an intense, hard-to-control hunger.

While on this page, you can learn more about these symptoms of BBS and why they occur, as well as find advice on managing them in yourself or an individual you care for living with BBS. Interested in additional information about BBS? Sign up to receive educational emails.

BBS Overview

What are the symptoms of BBS?

Signs and symptoms of Bardet-Biedl syndrome

The signs and symptoms of Bardet-Biedl syndrome may include:

The signs and symptoms of Bardet-Biedl syndrome (BBS) diagram

How is obesity measured?

Obesity is measured using what’s known as body mass index, or BMI. BMI is a measure of body fat based on height and weight.
  • In children, a BMI in the 95th percentile or higher is considered obesity
  • In adults, a BMI of 30 or higher is considered obesity

How is BBS inherited?

Bardet-Biedl syndrome is passed down from both parents through genes

Bardet-Biedl syndrome can be passed from parent to child if both parents have variants, or changes, in a BBS gene

Paul (Tanner’s father), Tanner (living with BBS), and Donna (Tanner’s mother)
BBS genes
One copy of the changed BBS gene is passed down from the mother, and the other copy is passed down from the father.
In people living with BBS, changes in BBS genes can stop a key part of the brain that controls hunger from working properly

Intense, hard-to-control hunger and obesity

What causes intense, hard-to-control hunger and obesity in someone living with BBS?

The key part of the brain that
communicates feeling hungry or
full is called the hypothalamus.
Hypothalamus and BBS

Think of the hypothalamus as a neighborhood within the brain

In this neighborhood, there are roads that allow cars to travel to and from the brain. One road is called the melanocortin-4 receptor, or MC4R, pathway. The cars on this road deliver messages between the body and the brain. These messages control hunger. On this road, there is a traffic light, or a BBS gene, that helps guide the cars to deliver their messages.

MC4R pathway

When the traffic light is working, the road is open, and the cars
can deliver messages to the brain that the body is full.

MC4R pathway

When the traffic light is broken, it causes a traffic jam. Because of
this, the cars can no longer deliver messages to the brain that the
body is full. Instead, the body believes that it is still hungry.

In people living with BBS, the traffic light is broken because of the change in their
BBS gene. As a result, the MC4R pathway may not work properly. This can lead to
intense, hard-to-control hunger and obesity.

How do you recognize intense, hard-to-control hunger in BBS?

Symptoms of intense, hard-to-control hunger can vary from person to person

Taking a longer time to feel full while eating

Taking a longer time
to feel full while eating

Feeling hungry again right after a meal

Feeling hungry again
right after a meal

Thinking about food constantly

Thinking about
food constantly

Food-seeking behavior (sneaking or stealing food)

Food-seeking behavior
(sneaking or stealing food)

My daughter tells me, ‘I know you are going to feed me, but it’s like I’m battling with my mind.’

–Caregiver of a child living with BBS

Caregiver quotes have been edited for clarity and conciseness.

Intense, hard-to-control hunger can have a negative impact on daily life for people living with BBS.

What can make living with intense, hard-to-control hunger so challenging?

Having constant hunger can make daily life stressful

Some have reported seeing these behaviors in themselves or an individual they care for

  • Arguing with or manipulating people to get food
  • Having tantrums to get food
  • Taking extreme measures to get food

For someone living with Bardet-Biedl syndrome, intense, hard-to-control hunger can affect other aspects of life

Thinking about food constantly
  • Trouble focusing at school or work because food is always top of mind
  • Difficulty socializing due to a constant pursuit of food
  • Psychological and emotional problems

Lots of stress…lots of worry…lots of guilt, too, because you have to tell him ‘no’ a lot…
We have to set strict boundaries for him, and he is not happy with that.

–Caregiver of a child living with BBS

Caregiver quotes have been edited for clarity and conciseness.

Is intense, hard-to-control hunger seriously affecting you or an individual you care for?
Complete this survey and share the results with your doctor.

Managing intense, hard-to-control hunger and obesity

Why is it important to manage hard-to-control hunger and obesity?

Addressing obesity in Bardet-Biedl syndrome can help avoid serious health issues

Obesity is a serious health problem for anyone. However, people living with BBS struggle with many health issues, all of which can be further complicated by obesity. That means it’s even more important to manage it from the start to help lessen the chance of serious complications later in life.

Serious health problems related to obesity can include:

  • Diabetes
  • High blood pressure
  • Heart-related issues (heart attack and stroke)
  • Orthopedic issues (problems with bones and muscles)

Making changes can have a positive influence. It’s good to know it’s not his fault, but we shouldn’t do nothing about it.

–Caregiver of a child living with BBS

Caregiver quotes have been edited for clarity and conciseness.

Ask your doctor about ways you or an individual you care for can address intense, hard-to-control hunger and obesity.

What are some ways to manage hard-to-control hunger and obesity?

Even though obesity in Bardet-Biedl syndrome is a matter of genetics, it is still important to eat a healthy diet low in sugars and high in vegetables, whole grains, and lean protein to help reduce the risk of diabetes and heart disease. Physical activity, such as taking a walk, is another simple way to help reduce your risk. As always, talk to your doctor about how diet and exercise can fit into your personal treatment plan. It can also be good to:

Actively seek out news and information about obesity in BBS to help give you a more complete understanding of the disease

Interested in additional information about BBS? Sign up to receive educational emails.

Learn from the first-hand experiences of individuals living with BBS and their caregivers

Watch videos about individuals living with BBS and their caregivers as part of the VOICES of RARE OBESITY series.

Download BBS brochure
Find helpful information in the Understanding BBS brochure
Take survey
Learn if intense, hard-to-control hunger is affecting you or an individual you care for living with BBS
View video of Izzy, who is living with Bardet-Biedl syndrome (BBS)

 

Leigh and her daughter Izzy
who lives with a rare genetic disease of obesity, share their story

IZZY
I would say my weight is my biggest challenge, and it affects every aspect of my daily activities.

LEIGH
It is really something that touches, it’s the cornerstone of her existence. It touches every part of her life that you can think of. Izzy has fatty liver disease that gets worse and worse the more weight that she gains, and she understands that. But it’s almost like an infinity symbol. It’s not even circular, because it is the most prevalent issue in Izzy’s life and in our family’s life.

LEIGH
It took five years until we actually had a diagnosis for her, for BBS, for her genetic condition. And I’ll tell you it was a very rough five years. We switched pediatricians probably 10 times. Izzy was referred to as having ‘Izzy syndrome’ because she had all of these different scattered symptoms, but nobody knew to put them all together. And as a mom you’re hoping you’re going to get a diagnosis, and everything’s going to be okay, we’re going to figure everything out. Well, when we finally got the diagnosis, it didn’t really do anything for us.

IZZY
It’s different for everyone, but for me it’s when I’m hungry I can’t stop it, cause I don’t have the signal from my brain, stomach to my brain that I’m full.

LEIGH
I always say I have three of the greatest humans that I know, and I’m extremely proud of them. Yeah, I’ll be very honest about it, it wasn’t the Hallmark ad with the kids holding their sibling in their lap and helping them and really embracing them. There was a lot of resentment there when they were growing up, because the world really did revolve around Izzy.

LEIGH
There’s all this talk in society about being heavy and losing weight, and it’s not something that’s understood. So she’s immediately discriminated against because of that. Because nobody’s going to believe, well I can’t control it. Well of course you can control it, you can control what you want to control. That’s not the case.

IZZY
When I was little I would like look at all these magazines of people, see people on TV and like, why can’t I be that…like people who are skinny, like, well why can’t I ever be like that? Like I’ll never be like that.

LEIGH
I know it’s a very sensitive subject for her. And she’s beautiful. And what do I always tell you? That you don’t need to look a certain way. You’re beautiful, you just need to feel a certain way. I wouldn’t push Izzy to do things that were discouraging and that she could not succeed at, but I raised Izzy saying you can do whatever it is that you want to do, and you need to set your mind to it.

LEIGH
I have always been a huge advocate for Izzy. I have a reputation that I don’t know if it’s good or bad, but when I’m advocating for something whether it be services or a new computer, whatever it may be for Isabelle, there’s really almost a tension in the air that is don’t mess with her, she’s not going to give up. Cause I love her so much.

IZZY
And I love you so much.

LEIGH
I know.

IZZY
I know.

LEADforRareObesity.com
facebook.com/LEADforRareObesity
Rhythm, LEAD for Rare Obesity, and their logos are trademarks of Rhythm Pharmaceuticals, Inc.
©2021 Rhythm Pharmaceuticals, Inc. All rights reserved. US-NP-2100210 12/2021

See the firsthand experiences of individuals living with BBS

View video of Izzy, who is living with Bardet-Biedl syndrome (BBS)

 

Leigh and her daughter Izzy
who lives with a rare genetic disease of obesity, share their story

IZZY
I would say my weight is my biggest challenge, and it affects every aspect of my daily activities.

LEIGH
It is really something that touches, it’s the cornerstone of her existence. It touches every part of her life that you can think of. Izzy has fatty liver disease that gets worse and worse the more weight that she gains, and she understands that. But it’s almost like an infinity symbol. It’s not even circular, because it is the most prevalent issue in Izzy’s life and in our family’s life.

LEIGH
It took five years until we actually had a diagnosis for her, for BBS, for her genetic condition. And I’ll tell you it was a very rough five years. We switched pediatricians probably 10 times. Izzy was referred to as having ‘Izzy syndrome’ because she had all of these different scattered symptoms, but nobody knew to put them all together. And as a mom you’re hoping you’re going to get a diagnosis, and everything’s going to be okay, we’re going to figure everything out. Well, when we finally got the diagnosis, it didn’t really do anything for us.

IZZY
It’s different for everyone, but for me it’s when I’m hungry I can’t stop it, cause I don’t have the signal from my brain, stomach to my brain that I’m full.

LEIGH
I always say I have three of the greatest humans that I know, and I’m extremely proud of them. Yeah, I’ll be very honest about it, it wasn’t the Hallmark ad with the kids holding their sibling in their lap and helping them and really embracing them. There was a lot of resentment there when they were growing up, because the world really did revolve around Izzy.

LEIGH
There’s all this talk in society about being heavy and losing weight, and it’s not something that’s understood. So she’s immediately discriminated against because of that. Because nobody’s going to believe, well I can’t control it. Well of course you can control it, you can control what you want to control. That’s not the case.

IZZY
When I was little I would like look at all these magazines of people, see people on TV and like, why can’t I be that…like people who are skinny, like, well why can’t I ever be like that? Like I’ll never be like that.

LEIGH
I know it’s a very sensitive subject for her. And she’s beautiful. And what do I always tell you? That you don’t need to look a certain way. You’re beautiful, you just need to feel a certain way. I wouldn’t push Izzy to do things that were discouraging and that she could not succeed at, but I raised Izzy saying you can do whatever it is that you want to do, and you need to set your mind to it.

LEIGH
I have always been a huge advocate for Izzy. I have a reputation that I don’t know if it’s good or bad, but when I’m advocating for something whether it be services or a new computer, whatever it may be for Isabelle, there’s really almost a tension in the air that is don’t mess with her, she’s not going to give up. Cause I love her so much.

IZZY
And I love you so much.

LEIGH
I know.

IZZY
I know.

LEADforRareObesity.com
facebook.com/LEADforRareObesity
Rhythm, LEAD for Rare Obesity, and their logos are trademarks of Rhythm Pharmaceuticals, Inc.
©2021 Rhythm Pharmaceuticals, Inc. All rights reserved. US-NP-2100210 12/2021

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