Why some people eat the same food every single day for years.

People with ADHD know how much the condition can affect all aspects of their life — from how well they do in school to their relationships. But many people with ADHD may not be as aware of just how much the condition can influence their eating habits. And if left unchecked, these poor eating habits could eventually affect their mental and physical health.

Some of the most common problems are "hyperfixation" and binge eating. Hyperfixation is an intense fixation on certain activities or interests but can include eating habits, too. This means some people may only eat a specific food or meal for a while, before becoming tired of it and moving on to a different food or meal.

Studies have also shown an association between ADHD and certain eating disorders, with binge eating disorder being one of the most common. Binge eating disorder is when people consume large amounts of food over a short time, even when they're not hungry. It's estimated that almost a third of people in the US who have binge eating disorder also have ADHD.

Watch: How ADHD can affect relationships. Post continues after video.

Some experts believe that people with ADHD may overeat to satisfy their need for stimulation. Binge eating may also happen because ADHD makes it difficult for people to have self-control and self-regulation, meaning they may be more likely to overeat if they're feeling sad or angry, and they may not find it as easy to know when they're full.

Some evidence suggests that binge eating in people with ADHD may be attributed to a heightened neural reward response to food rather than impulsivity. This is when the brain is exposed to a stimulus that is rewarding and responds by releasing an increased amount of dopamine, a chemical in the brain associated with reward and pleasure. However, impulsiveness (another symptom of ADHD) may also lead people to overeat — especially foods that are unhealthy.

Some ADHD drugs can also suppress appetite during the day. But as the drug's effects wear off in the evening, appetite increases, which may lead to binge eating.

Sensory issues may also explain why some people with ADHD tend to eat or avoid certain foods. Certain textures or smells may cause sensory overload, making it difficult for people with ADHD to eat them — leading to avoidance of those foods or food groups altogether.

There's also evidence that people with ADHD tend to gravitate toward junk foods, especially food that is high in sugar. This may be because high-sugar foods stimulate the release of dopamine.

People with ADHD have lower levels of dopamine. As such, they may be more "wired" to seek dopamine out. Since eating simple carbohydrates (such as high-sugar foods) triggers a rush of dopamine in the brain, this may be why people with ADHD tend to hyperfixate or binge on these foods.

Listen to this episode of No Filter where Mia Freedman shares the story of when she was diagnosed with ADHD at the age of 49. Post continues after podcast.

What about nutrition?

Not having a varied diet or only eating foods that may be high in sugar can lead to a range of health problems from vitamin deficiencies to obesity. High-sugar diets can also affect energy levels and mood.

Some preliminary research suggests that certain foods, for example, highly processed, additives and preservatives, may also change behaviour and cognitive development.

Several studies have shown nutritional deficiencies can affect behaviour and cognitive function in people with ADHD. Vitamin D and magnesium in particular are important, with research showing they may improve attention and decrease hyperactivity somewhat. Vitamin D can also affect the way dopamine forms in the brain.

But even though ADHD can make it harder to keep eating habits in check, if you have ADHD there are things you can do to improve the situation. Here are some of them:

• Plan: Shop and plan meals for the week ahead. Planning meals makes it easier to decide what and when to eat and may help you avoid buying or bingeing on unhealthy, processed foods.
• Eat small but nutritious meals throughout the day. If these are planned, it can help you avoid filling up on unhealthy snacks — and may also help you avoid evening binges if you're someone who forgets to eat throughout the day. A balance of protein and complex carbohydrates (such as chicken, beans or whole grains) will help you get enough proper nutrients and vitamins, but will also help you feel fuller for longer and give you energy.
• Create a healthy food environment at home. This might involve not buying high-calorie snacks or replacing them with nutritious ones instead – such as fruit or vegetables, which may help improve your attention.
• Supplement certain vitamins and minerals. People with ADHD are more likely to be deficient in certain micronutrients including omega-3, magnesium and zinc. These nutrients are important for ensuring the brain, body and immune system all function at their best.

Want to learn more about ADHD? Read our top recommendations:

• 'I discovered I had ADHD.' 10 women on the most surprising thing about giving up alcohol.
• Why are women with ADHD underdiagnosed?
• How is adult ADHD different to childhood ADHD?

Featured Image: Getty.