Dementia And Weight

What is dementia?

Dementia is an illness identified by a downward decline in reasoning and ability to function properly.1 It is not a specific brain disease but the general term for symptoms that indicate an impairment in thinking, reasoning, and memory.2

Symptoms of dementia

Dementia brings about changes in reasoning, performance, and behaviour. The symptoms of dementia usually start gradually, become persistent and continue to worsen over time.  According to the Alzheimer’s Society of Canada,3 symptoms of dementia include:

  • Memory loss affecting daily activities
  • Difficulty remembering familiar places and things, thus wandering or pacing
  • Difficulty performing tasks they are familiar with
  • Forgetting or mixing up words
  • Changes in judgment or decision making
  • Confusion with time; not remembering what day or time it is
  • Problems with abstract thinking
  • Changes in mood or behaviour
  • Misplacing things
  • Changes in personality
  • Loss of interest
  • Changes in vision and in the ability to calculate distance, space, and height

The later stage of dementia includes more prominent behavioural and psychological symptoms of dementia (BPSD). A person with dementia might experience behavioural changes, delusions, and hallucinations. They will also experience physiological changes which increase their chances of getting infections; changes such as falling frequently, unintentional weight loss, difficulty swallowing, inability to walk steadily, and control their bowel and bladder.4,5

Unintentional weight loss is common with dementia

As dementia progresses, an individual with dementia will start losing weight, which is seen in the later stages of the illness. The brain controls many functions in the body, including hunger and fullness, which makes scientists believe the effects of dementia in the brain will also affect other bodily functions, including weight.7 This unintentional weight loss results from the symptoms of dementia which range from pacing, restlessness, forgetting to eat, not being able to recognize food, not being able to perform simple tasks like feeding themselves; and this  worsens as the disease progresses.6 The restlessness and pacing, among other activities carried out by an individual with dementia, will make them burn more calories, contributing to weight loss.7

Unintentional weight loss is so common that it is estimated that 30-40% of people with dementia will experience significant weight loss due to a reduction in nutritional status stemming from poor food intake. Research shows that 14-45% of patients with mild to moderate, and 68% of those with severe Alzheimer’s Disease, the leading cause of dementia, are at risk of malnutrition.8,9

A study by the Journal of Nurse Practitioners suggested that living alone, older age and inability to function contribute to nutritional risks that are aggravated by cognitive decline.6 The chances of unintentional weight loss in dementia are higher in patients having one or more medical conditions such as depression, diabetes, pain, cancer, thyroid disease, constipation, dehydration, gastrointestinal disorders like peptic ulcer, dry mouth, poorly fitting dentures, mouth ulcers, bad teeth, and end-organ diseases like heart failure or kidney failure. These conditions can also be a side effect of medication for Alzheimer’s and other underlying medical conditions.7

Obesity is a risk factor for dementia

There are several risk factors for dementia, and obesity in the middle-aged people (approx. 45-65 years) has been shown to be one of the top risk factors for developing dementia in older age.10  The results from research suggest that changes in the body mass index and abdominal obesity also impact the incidence of dementia.11,12 

Obesity and dementia share similar risk factors such as age, lack of exercise, socioeconomic status, genes, gender, environment, depression, and a high-fat diet.12 Obesity is the excessive accumulation of fat in the adipose tissue or fat cells, which leads to a low-grade inflammatory state.13 This inflammatory state leads to unregulated food intake and insulin resistance, which has a complex underlying mechanism with dementia.12,13,14  Both conditions are associated with multiple common conditions that arise from obesity and can have negative effect on the brain. These include diabetes, hypertension and cardiovascular disorders. The NHS suggests that losing 5-10% of excess weight can help prevent dementia.15

Interestingly, the research literature on the link between dementia and obesity is highly incongruent. For instance, a research study recruited 10,308 participants aged 35 to 55 who were followed up for 30 years. The results suggested that obesity at the age of 50 was a risk factor for dementia. However, obesity later in life, at the age of 60 or 70 years, was not a risk factor for dementia.12 That said, a more recent large-scale study identified obesity to have a somewhat protective effect against dementia, with people in class III obesity (BMI of 40 or more) having a 29% lower risk of dementia compared to people with normal weight. These findings have been attributed to the fact that people with high BMI are more likely to pass away due to diabetes or cardiovascular conditions before receiving the diagnosis of dementia, thereby skewing the results.  

Inflammation promotes neuronal damage

Obesity is a risk factor for type 2 diabetes, and diabetes causes chronic inflammatory damage to brain cells. During this pro-inflammatory state, insulin resistance causes a chain reaction that leads to cellular stress in the brain, including the hippocampus, which controls thoughts, emotion, and the nervous system. 

Obesity is also a top risk factor for nonalcoholic fatty liver disease (NAFLD). This chronic liver disease that causes a buildup of fat in the liver of people who drink little to no alcohol.16 NAFLD puts you at moderate risk for dementia, and increases the dementia risk if you have co-occurring heart disease.17

This stress in the brain can result in Alzheimer's disease, also known as type 3 or brain diabetes, in 60% of people with type 2 diabetes. Alheimer’s disease occurs when there is a buildup of plaques of beta-amyloid protein between nerve cells, causing neuronal sepsis, the point where cells start to die.14


Obesity and dementia are both somewhat preventable conditions (except if it has familial history), and they are associated. Eating healthy, reducing high-fat foods, and introducing regular exercise can mitigate the chances of excess weight and diagnosis of dementia later in life.


  1. Duong, Silvia, et al. “Dementia.” Canadian Pharmacists Journal : CPJ, vol. 150, no. 2, Feb. 2017, pp. 118–29. PubMed Central,
  2. What Is the Difference between Dementia and Alzheimer’s Disease? | Alzheimer’s Society. Accessed 22 Sept. 2022.
  3. “The 10 Warning Signs of Dementia.” Alzheimer Society of Canada, Accessed 27 Sept. 2022.
  4. The Later Stage of Dementia | Alzheimer’s Society. Accessed 22 Sept. 2022.
  5. Gottesman, Reena T., and Yaakov Stern. “Behavioral and Psychiatric Symptoms of Dementia and Rate of Decline in Alzheimer’s Disease.” Frontiers in Pharmacology, vol. 10, 2019. Frontiers,
  6. Lopez, Ruth Palan, and Sheila L. Molony. “Dementia: Weight Loss and Mealtime Challenges.” The Journal for Nurse Practitioners, vol. 14, no. 3, Mar. 2018, pp. 153–59.,
  7. “Weight Loss in Alzheimer’s Disease.” Cleveland Clinic, Accessed 29 Sept. 2022.
  8. What Is Dementia? | CDC. 19 Dec. 2019,
  9. Franx, Bart A. A., et al. “Weight Loss in Patients with Dementia: Considering the Potential Impact of Pharmacotherapy.” Drugs & Aging, vol. 34, no. 6, June 2017, pp. 425–36. (Crossref),
  10. Roh, Eun, et al. “Body Weight Variability Increases Dementia Risk Among Older Adults: A Nationwide Population-Based Cohort Study.” Frontiers in Endocrinology, vol. 11, 2020. Frontiers,
  11. Ma, Yixuan, et al. “Higher Risk of Dementia in English Older Individuals Who Are Overweight or Obese.” International Journal of Epidemiology, vol. 49, no. 4, Aug. 2020, pp. 1353–65. (Crossref),
  12. Singh‐Manoux, Archana, et al. “Obesity Trajectories and Risk of Dementia: 28 Years of Follow‐up in the Whitehall II Study.” Alzheimer’s & Dementia, vol. 14, no. 2, Feb. 2018, pp. 178–86. (Crossref),
  13. Flores-Cordero, Juan Antonio, et al. “Obesity as a Risk Factor for Dementia and Alzheimer’s Disease: The Role of Leptin.” International Journal of Molecular Sciences, vol. 23, no. 9, May 2022, p. 5202. (Crossref),
  14. Selman, Ashley, et al. “The Role of Obesity and Diabetes in Dementia.” International Journal of Molecular Sciences, vol. 23, no. 16, Aug. 2022, p. 9267. (Crossref),
  15. “Can Dementia Be Prevented.” Nhs.Uk, 21 Dec. 2017,
  16. Fabbrini, Elisa, et al. “Obesity and Nonalcoholic Fatty Liver Disease: Biochemical, Metabolic, and Clinical Implications.” Hepatology, vol. 51, no. 2, Feb. 2010, pp. 679–89. (Crossref),
  17. Shang, Ying, et al. “Nonalcoholic Fatty Liver Disease and Risk of Dementia: A Population-Based Cohort Study.” Neurology, vol. 99, no. 6, Aug. 2022, pp. e574–82.,

Chimezirim Ozonyiri

Bachelor of Science - BS, Microbiology, General, Tansian University, Nigeria

Chimezirim has several years of experience in the healthcare, non-profit, and education sectors. She is passionate about health promotion and began her journey into health and lifestyle writing over two years ago. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818