ADHD, CrossFit and nutrition

Meyken Houppermans, PhD. CrossFit Level 3 Trainer.
Founder and Head Coach
CrossFit is a coach- led training program with features of a military program. It is structured and directive, and it requires mental focus, discipline and perseverance. Not something you would immediately associate with ADHD, or is it?

ADHD: Psychiatric disorder or neuro-diversity

ADHD (Attention Deficit-Hyperactivity Disorder) is a psychiatric condition in which individuals show behavioral patterns of inappropriate levels of inattentiveness, hyperactivity, or impulsivity (inappropriate within the context of what is developmentally and culturally appropriate).

A complementary approach is ADHD as a form of neuro-diversity in which a person processes information differently and has different ways of thinking and learning. The use of the term neuro-diversity can help to reduce the potentially negative connotation of ADHD, compared to using the term psychiatric disorder.

In the past, the diagnostic distinction was made between ADD (Attention Deficit Disorder) and ADHC. Now, this is combined to one disorder (ADHD) with three subtypes:

1.       Predominantly inattentive: having difficulty keeping attention (former ADD)

2.       Predominantly hyperactive: being very busy, always moving, speaking without thinking

3.       Combined: a combination of inattentive and hyperactive 

In adults, ADHD symptoms may be different than in children. It is likely that adults can control hyperactivity symptoms better while other symptoms such as impulsiveness, inattentiveness, mood swings and low self- esteem are more present. [1]

Possible causes of ADHD

It is known that the brain of people with ADHD works differently than those of people without ADHD, and these differences in the brain might affect dopamine and noradrenaline levels. A possible mechanism for ADHD might be a loss of executive functions of the pre-frontal cortex of the brain such as goal-directed behavior, mood- regulation, decision making, emotional control, and the ability to integrate various demands and emotions.

ADHD is one of the most heritable psychiatric conditions, but having a genetic predisposition does not necessarily mean a person will develop ADHD. Other factors also play a role such as premature birth, low birth weight, viral infections, smoking and drinking alcohol during pregnancy, stress during pregnancy, and nutritional deficiency. Furthermore, children who grow up in an environment with a lot of strife and stress seem to be more likely to develop ADHD.[2]

Prevalence and diagnose in adults

The prevalence of ADHD in children is 6 to 9 %, and around 40 to 70% of them will experience symptoms as adults. It is estimated that 3 to 6% of the adult population has ADHD symptoms that interfere with daily and social functioning. ADHD seems twice as common in men than in women. 

ADHD is considered one of the most prevalent psychiatric disorders. The diagnose in adults is often missed for example because people have multiple problems often seemingly not related to ADHD; or people adapt their lives to their behavioral ‘abnormalities’.

Diagnose is relevant because adults with ADHD have poorer psychosocial outcomes such as higher rates of incarceration, work instability and addictions. 50% of adults with ADHD have multiple psychiatric disorders such as depression, bipolar disorders, anxiety and personality disorders. Furthermore, people with ADHD have a higher risk of other mental disorders such as dementia. A diagnose can not only be helpful to get treatment, but also to raise understanding from family, friends and colleagues and thereby getting more support and making daily life and relationships easier.[3]

Treatment: multi- faced approach

It seems that 50% of children with ADHD outgrow their symptoms with treatment, and another 25% without treatment. Possibly because medication helps to improve the development of the brain over time, and because as adults they often choose careers that do not require sustained attention and therefor they do not report symptoms.

For adults, diagnose and treatment is important because untreated ADHD can cause ongoing dysfunction and can have devastating consequences such as loss of work and relationships, increased risk of accidents and addictions, and substance abuse.

In adults with ADHD, a combination of medication, psychosocial therapy and lifestyle adjustments seems effective in reducing symptoms. Psychosocial therapy refers to psycho-education for family, friends and the person with ADHD as well as cognitive-behavioral therapy for the person with ADHD to achieve short and long-term goals. Lifestyle adjustments refer to nutrition, exercise and sleep.[4]

Nutrition and ADHD

Research on the impact of nutrition on ADHD is inconclusive. Although there is no clear evidence that nutrition can treat ADHD, there are indications that nutrition plays some role in reducing or worsening symptoms, and that people with ADHD can benefit from a healthy lifestyle, just like people without ADHD.[5]

It seems unhealthy nutrition is positively associated with ADHD, and an unhealthy dietary pattern seems to contribute to a higher risk (41%) of developing ADHD. This concerns the intake of junk food, ultra-processed foods (How artificial is your food?), snacks, sweets, fried foods and salt. Research regarding the association between solely sugar and ADHD is inconclusive. A Western- style diet with red and processed meat (How bad is eating meat?), soft drinks, processed foods and refined cereal grains, seems to increase the risk of ADHD with 92%. Junk food with a high intake of processed foods, fat, sugar and especially artificial food coloring seems to increase the risk with 50%. Artificial food coloring such as in sweets can affect the brain, brainwave activity and ADHD symptoms.

Healthy nutrition, such as the Mediterranean diet and vegetarian diets, seems negatively associated with ADHD and a healthy dietary pattern seems to have a protective effect on the development of ADHD (37% less risk). This concerns the intake of fruits, vegetables, fish, poly-unsaturated fats and foods high in magnesium, zinc and phyto- chemicals (To soy or not to soy?).

Children with ADHD seem to have reduced levels of several minerals such as zinc, copper, iron, magnesium and selenium, and of vitamins such as vitamin A en D. However, research shows it is not a single nutrient that seems associated with ADHD, but it is the dietary pattern (unhealthy or healthy) as a whole. One possible explanation is that nutrients in food interact in very complex ways and their impact on the brain is determined in part by food composition, preparation methods and the unique way a person responds to food (Your friend loses weight, you don't. Why?). The challenging aspect is that children with ADHD show less adherence to a healthy diet than children without ADHD.

In general, a healthy wholesome diet provides all the vitamins and minerals the body and brain need. Nutritional supplementation is then in principle unnecessary (Do you need supplements?). Research shows only vitamin D and/ or magnesium supplementation can alleviate ADHD symptoms in cases of deficiencies. Furthermore, there seems some evidence regarding the positive effect of Lactobacillus rhamnosus GG such as in fermented products (yoghurt, kefir, kimchi, sauerkraut, tempeh). There is no evidence regarding the effect of elimination diets on ADHD, and often these diets lead to nutritional deficiencies (Are you on a Fad diet?).[6]

Exercise and ADHD

Regular exercise seems to be beneficial for adults with ADHD, specifically mixed exercise programs at moderate and high intensity such as CrossFit. In most cases this seems to alleviate several cognitive, physical and behavioral symptoms of ADHD such as attention, learning and concentrating, and motor skills. There seems to be no negative effects known of exercise on ADHD.[7]

Research shows cardio exercise seems to have acute and chronic benefits for overall executive functions in people with ADHD and for example on impulse control, attention, and cognitive flexibility. The effects of non- cardio exercise are less clear but still seem positive. Furthermore, there are indications of positive effects of qualitative exercise characteristics on people with ADHD, such as exercise that demands mental focus, cognitive effort and skill learning. Characteristics of CrossFit.[8]

The comprehensive program of CrossFit integrates cardio, strength, balance, skill training and functionality, provides structure and requires mental focus. The tailoring of training sessions to the level and needs of the participants and the professional coaching, can precisely be a suitable environment for people with ADHD.

There are no recommendations regarding frequency, intensity, or duration of exercise, specific to people with ADHD. The general exercise recommendations (the minimum level) to maintain current health for adults with and without ADHD are:

-           Do at least 2,5 to 5 hours of moderate-intensity aerobic activity, or at least 1,25 to 2,5 hours of high-intensity aerobic activity throughout the week

-           Do muscle-strengthening activities at moderate or high intensity that involve all major muscle groups on 2 or more days a week

-           Minimize the time spend sedentary

-           Additionally for adults above 65 years, do functional balance and strength training at moderate or greater intensity at least 3 or more days a week

To improve current health and to reduce the negative effects of a sedentary lifestyle (such as having a desk job) all adults should aim to do more than these recommendations, according the World Health Organization. Regular exercise is beneficial for mental and cognitive health and for sleep.[9]

Sleep and ADHD

It seems around 80% of adults with ADHD experience sleep problems. People with subtype 2 and 3 (hyperactive or combined ADHD subtype) often have a genetic predisposition for falling asleep only late at night. People with subtype 1 (formerly know as ADD), sleep differently and often go to bed earlier, sleep longer, and are nevertheless often tired during the day.

Research shows melatonin levels in people with ADHD rise around 90 minutes later than in people without ADHD. In people with ADD, this is 30 minutes later.

Sleep is a crucial for health, and sleep disorders can lead to several diseases such as obesity, diabetes type 2, cardiovascular diseases and even increase the risk of preliminary death (Sleep, CrossFit and Health). Prescribed and supervised use of melatonin in the evening and light therapy in the morning can be part of the treatment of ADHD. Melatonin can help to improve sleep. In addition, melatonin seems to reduce the severity of ADHD by 14%.

Supervised use seems important because over-the-counter melatonin is often misused, which can lead to worsening of sleep problems. The challenge, as also mentioned regarding the adherence to a healthy diet, for people with ADHD is to adhere to their medication.[10]


On the one hand, the number of children, adolescents and adults with mental problems and the number of people diagnosed with ADHD seem to be increasing. On the other hand, the number of lifestyle-related disorders is increasing and there is exercise poverty. This while more and more is known about the importance of a healthy lifestyle, of healthy nutrition, good sleep and regular exercise for physical, mental and emotional health.

In sports such as CrossFit, attention to mental health is essential, and the sport should not only revolve around physical health and athletic performance. In healthcare, among health care providers, attention to sport and lifestyle and its importance for effective treatment is essential.

Lifestyle factors cannot cure ADHD, but they can alleviate the symptoms of ADHD and thereby improve the daily lives of people with ADHD and those around them. If, for example, through effective treatment and a healthy lifestyle, people with ADHD are better able to do perform at work and keep their job, maintain relationships, experience fewer mental problems, have less addiction tendencies and make fewer claims for care and welfare, this can save society a lot of costs.


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[2] Hersenstichting. Hersenaandoeningen.ADHD. Retrieved June 2024 via;Kates N. Attention deficit disorder in adults. Management in primary care. CanFam Physician. 2005 Jan;51(1):53-9. PMID: 15732222; PMCID: PMC1479568.; Magnus W, Nazir S, Anilkumar AC,Shaban K. Attention Deficit Hyperactivity Disorder. 2023 Aug 8. In: StatPearls[Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan–. PMID:28722868.

[3] Idem 

[4] Idem 

[5] Cagigal, Cesar., Silva, Tania., Jesus Mariana., Silva, Carla. (2019). Does Diet Affect the Symptoms ofADHD?. In: CurrentPharmaceutical Biotechnology, volume 20, issue 2, pages 130-136, year 2019,issn 1389-2010/1873-4316, doi 10.2174/1389201019666180925140733. 

[6] PintoS, Correia-de-Sá T, Sampaio-Maia B, Vasconcelos C, Moreira P, Ferreira-Gomes J.Eating Patterns and Dietary Interventions in ADHD: A Narrative Review. Nutrients.2022 Oct 16;14(20):4332. doi: 10.3390/nu14204332. PMID: 36297016; PMCID:PMC9608000.

[7] Ng QX, Ho CYX, Chan HW, Yong BZJ, Yeo WS.Managing childhood and adolescent attention-deficit/hyperactivity disorder(ADHD) with exercise: A systematic review. Complement Ther Med. 2017Oct;34:123-128. doi: 10.1016/j.ctim.2017.08.018. Epub 2017 Aug 31. PMID:28917364.

[8] Ahmed, G. M., & Mohamed, S.(2011). Effect of regular aerobic exercises on behavioral, cognitive andpsychological response in patients with attention deficit-hyperactivitydisorder. Life Sci J8(2), 366-371.; Den Heijer AE, Groen Y, Tucha L, Fuermaier AB, KoertsJ, Lange KW, Thome J, Tucha O. Sweat it out? The effects of physical exerciseon cognition and behavior in children and adults with ADHD: a systematicliterature review. J Neural Transm (Vienna). 2017 Feb;124(Suppl 1):3-26. doi:10.1007/s00702-016-1593-7. Epub 2016 Jul 11. PMID: 27400928; PMCID: PMC5281644.;Liang X, Li R, Wong SHS, Sum RKW, Sit CHP. The impact of exercise interventionsconcerning executive functions of children and adolescents withattention-deficit/hyperactive disorder: a systematic review and meta-analysis.Int J Behav Nutr Phys Act. 2021 May 22;18(1):68. doi:10.1186/s12966-021-01135-6. PMID: 34022908; PMCID: PMC8141166..; NeudeckerC, Mewes N, Reimers AK, Woll A. Exercise Interventions in Children andAdolescents With ADHD: A Systematic Review. J Atten Disord. 2019Feb;23(4):307-324. doi: 10.1177/1087054715584053. Epub 2015 May 11. PMID:25964449..

[9] World Health Organization. (Oct2022). Physical Activity. Retrieved June 2024 via:

[10] Psyq. ADHDen slaapproblemen. Retrieved June2024 via: