Understanding Weight Loss in Parkinson’s
Weight loss is a common but often overlooked problem in Parkinson’s Disease (PD). Research shows that people with PD lose significantly more weight than others their age, about 8 pounds over a decade. Weight loss may even begin 5 to 7 years before you receive your diagnosis. Understanding the many causes of weight loss can help you work with your healthcare team to maintain your health and quality of life.
The Many Causes of Weight Loss in Parkinson’s Disease
Weight loss in PD is “multifactorial,” meaning it results from many different factors working together. These include:
1. Gastrointestinal Dysfunction
Parkinson’s disease affects the entire digestive system, from mouth to bowel:
- Dysphagia (difficulty swallowing): This is very common in PD. PD affects areas in the brain responsible for coordinating the swallowing reflex. Rigidity and slowness the tongue and throat muscles can make it hard to move food safely, increasing the risk of aspiration (food entering the airway) and reducing how much you can eat.
- Gastroparesis (delayed stomach emptying): This affects almost everyone with PD. When your stomach empties slowly, you may feel full quickly (early satiety), experience nausea, or feel bloated, all of which reduce appetite and food intake.
- Constipation: This is very common in PD. Chronic constipation can cause discomfort and reduce appetite.
- Enteric nervous system (ENS) involvement: The ENS is sometimes called “the second brain” because it controls the gut. In PD, the gut’s nerve networks are often affected very early in the disease which result in abnormal gut function.
- Gut microbiome dysbiosis: The gut microbiome refers to the trillions of bacteria living in your intestines. Research shows that people with PD who are underweight have different bacterial populations, specifically more pro-inflammatory bacteria. This imbalance may contribute to inflammation and muscle wasting.
2. Hormonal Changes
The hypothalamus is a brain region that regulates hunger and energy balance. This area can be affected in PD, disrupting the normal hormones that control appetite. As a result, your body may not send proper hunger signals even when you need to eat, and the normal responses that should increase appetite when you lose weight may be blunted.
3. Metabolic and Energy Factors
- Glucose metabolism impairment: People with PD often have problems with blood sugar regulation, which can lead to a low-energy state at the cellular level.
- Mitochondrial dysfunction: Mitochondria are the “powerhouses” of your cells that produce energy. Research strongly links mitochondrial problems to PD, creating a “bioenergetic deficit” where cells cannot produce enough energy even when adequate calories are consumed. This may explain why some people with PD lose weight despite eating normally or even more than usual.
- Resting energy expenditure: Some studies suggest that involuntary movements (dyskinesias) and muscle rigidity may increase the number of calories your body burns at rest, contributing to weight loss.
4. Sensory Changes
Anosmia (loss of smell): This is very common in PD, often occurring years before motor symptoms appear. Because smell and taste are very closely linked, food may become less appealing, reducing your desire to eat.
5. Cognitive and Psychological Factors
- Depression: Depression is the most common psychiatric symptom in PD and can significantly reduce appetite through loss of interest in food, decreased motivation, and anhedonia (inability to feel pleasure, including from eating).
- Cognitive impairment: Memory and executive function problems can make it difficult to plan meals, shop for groceries, prepare food, and remember to eat regularly.
- Reward circuit dysfunction: PD affects brain circuits involved in motivation and reward which may decrease the drive to eat.
6. Medication Effects
Levodopa: This cornerstone PD medication can cause nausea and other gastrointestinal side effects that reduce appetite. Levodopa is also associated with dyskinesias, which may increase calorie expenditure.
Dopamine agonists: Medications like pramipexole and ropinirole may actually have a protective effect against weight loss, possibly through direct effects on appetite and metabolism.
Information About Levodopa and Protein
Levodopa is absorbed in your small intestine through the same transport system that absorbs amino acids (the building blocks of protein). When you eat a high-protein meal, including meat, fish, eggs, dairy products, beans, or nuts, the amino acids can compete with levodopa for absorption, potentially reducing how much medication reaches your brain.
However, this interaction only significantly affects about 10-20% of people with PD. Most people do not notice a meaningful difference in their medication effectiveness based on protein intake.
Practical recommendations:
- Do not eliminate protein: Protein is essential for maintaining muscle mass and overall health, especially important when you are at risk for weight loss.
- Pay attention to your own response: If you notice your medications seem less effective after high-protein meals, try taking levodopa 30 to 60 minutes before meals or 1 to 2 hours after eating.
Why Maintaining Weight Matters
Research shows that weight loss in PD is associated with:
- Increased frailty: Frailty is a state of decreased physical reserves that makes you more vulnerable to illness, falls, and slower recovery. Low weight is a key marker of frailty.
- Higher mortality: Studies consistently show that lower body mass index (BMI) is associated with poorer survival in PD.
- Reduced quality of life: Data from Parkinson’s centers of excellence found that every one pound of weight loss is associated with a 0.5% reduction in health-related quality of life.
- Faster cognitive decline: People with PD who lose weight show faster declines in thinking and memory compared to those who maintain or gain weight.
- Increased fatigue and depression: Weight loss has been linked to greater fatigue, reduced physical stamina, and worsening mood.
Screening and Monitoring
Weight loss in PD is often under-recognized. You should:
- Weigh yourself regularly: Keep a log of your weight to share with your healthcare team.
- Know the warning signs: Weight loss greater than 5% in 3 months or greater than 10% in 6 months is considered clinically significant and indicates higher risk for malnutrition.
- Report unintentional weight loss: Tell your doctor if you are losing weight without trying, even if the amount seems small.
Management Strategies
Nutritional interventions:
- Eat small, frequent meals: If large meals feel overwhelming or cause nausea, try 5 to 6 smaller meals throughout the day.
- Choose calorie-dense foods: Focus on foods that provide more calories in smaller portions, such as nut butters, avocados, olive oil, cheese, and smoothies made with full-fat yogurt or protein powder.
- Optimize protein intake: Ensure adequate protein to maintain muscle mass. If you are among the minority affected by protein-levodopa interactions, work with your care team on timing strategies.
- Stay hydrated: Drink plenty of fluids, but avoid filling up on low-calorie beverages before meals.
- Consider nutritional supplements: Oral nutritional supplements (such as Ensure, Boost, or similar products) can help increase calorie and protein intake when eating is difficult.
Address swallowing difficulties:
- Request a swallowing evaluation: If you have trouble swallowing, cough during meals, or feel like food gets stuck, ask your doctor for a referral to a speech-language pathologist for a formal swallowing assessment.
- Modify food textures: Depending on your swallowing function, you may benefit from softer foods, thickened liquids, or other texture modifications.
- Use safe swallowing techniques: A speech therapist can teach you positioning and swallowing strategies to reduce aspiration risk.
Manage constipation:
- Increase fiber gradually: Fruits, vegetables, whole grains, and legumes can help, but increase fiber slowly to avoid bloating.
- Drink adequate fluids: Aim for 6 to 8 glasses of water daily unless otherwise directed by your doctor.
- Stay physically active: Movement helps stimulate bowel function.
- Discuss medications: Talk to your doctor about stool softeners, osmotic laxatives, or other treatments if dietary changes are insufficient.
Address gastroparesis:
- Eat smaller portions: Large meals can worsen delayed stomach emptying.
- Limit high-fat foods: Fat slows gastric emptying; lower-fat options may be better tolerated.
- Stay upright after eating: Avoid lying down for at least 1 to 2 hours after meals.
Treat depression and apathy:
- Talk to your doctor: Depression is treatable with medications, therapy, or both. Improving mood often improves appetite.
- Stay socially engaged: Eating with others can make meals more enjoyable and increase food intake.
Work with specialists:
- Speech-language pathologist: For swallowing evaluation and therapy.
- Gastroenterologist: For persistent digestive symptoms that do not respond to initial treatments.
- Psychiatrist or psychologist: For depression, anxiety, or other mood concerns.
- Registered dietitian: A dietitian familiar with PD can create a personalized nutrition plan that addresses your specific challenges.
Author Mick Reedy, MD, is a Movement Disorders Specialist with
Inova Parkinson’s and Movement Disorders Center (IPMDC)