As we get older, not only does our body change on the outside, but the way it works on the inside also slows down. One major change is that our metabolism – the process that turns food into energy - gradually becomes slower. The basal metabolic rate, which is the amount of energy (calories) our body needs just to stay alive (such as breathing and keeping our heart beating), decreases. This is often due to becoming less active and losing muscle mass. If we continue eating the same amount of food as we did when we were younger, we’re more likely to gain weight.

Other common changes with age include becoming more resistant to insulin, which makes it harder for the body to handle sugar and increases the risk of diabetes. Inflammation in the body also tends to rise, which can lead to various health problems. Hormone levels shift as well – there’s less growth hormone and fewer sex hormones, which affects energy levels, strength, and overall health.

We may also feel more tired, partly because the mitochondria (the organelles in our cells that produce energy) don’t function as efficiently as they used to. This decline affects all bodily functions, including the immune system, making us more vulnerable to illness.
Another issue that often goes unaddressed in the media is that our bodies become less efficient at absorbing nutrients from food. As a result, it’s easier to develop vitamin and mineral deficiencies – even with a good diet - which can, in turn, accelerate physiological aging.

Research shows that even without dietary restrictions elderly people are at risk of developing nutrient deficiencies, such as:

VITAMINS

•    Vitamin D: Crucial for bone health and calcium absorption. Deficiency is linked to reduced synthesis of this vitamin in the skin, limited time spent outdoors, and low dietary intake. Additionally, higher body fat levels can store fat-soluble vitamins (D, E, A, and K), reducing their availability for metabolic processes.
•    Vitamin B12: Vital for nerve function, red blood cell formation, and immune health. Its intestinal absorption depends on the intrinsic factor, the production of which decreases with age.
•    Vitamin C: Essential for healthy skin, bones, heart, liver, immune function, detoxification, and overall organ health. The human body cannot produce vitamin C; it must be obtained from food or supplements.
•    Folic Acid: Important for red and white blood cell production and immune function.

MINERALS

•    Calcium: Essential for bone strength and density and also for muscle contractions, nerve signal transmission, blood clotting, among others.
•    Potassium: Supports healthy bones and helps regulate blood pressure.
•    Magnesium: Important for muscle and nerve function, blood pressure regulation, and bone health.
•    Iron: Necessary for energy production and preventing anemia.

OTHER NUTRIENTS

•    Fiber: Supports healthy digestion, regulates blood sugar and cholesterol levels, and aids in weight management. It also provides fuel for beneficial gut bacteria, lowering the risk of chronic diseases such as heart disease, type 2 diabetes, and certain cancers.
•    Protein: The primary building block of our bodies including muscles, bones, skin, and blood. It is essential for growth, tissue repair, and maintaining lean muscle mass. Protein also supports the immune system by aiding in the production of antibodies and immune cells essential in fighting infections and protecting our bodies from diseases. 
•    Omega-3 Fatty Acids: Support cognitive function and reduce inflammation.

Why losing excess weight can help – but strict diets can be risky for older adults

While losing excess weight can help manage conditions like diabetes, high blood pressure, and kidney disease, overly restrictive diets can pose significant risks for older adults.

Beyond the metabolic effects, drastic dietary changes can be psychologically overwhelming for some individuals, potentially triggering anxiety or depression. These changes may also create additional burdens – such as the need to prepare special meals, avoid shared meals, or skip family gatherings – leading to increased social isolation.

Therefore, weight-loss diets must be carefully planned and tailored to each individual's health needs. If not appropriately managed, they can cause more harm than good, potentially resulting in weakness, malnutrition, or other health issues.

Key Concerns with Restrictive Diets in Older Adults

Restrictive diets (e.g., very low-fat, low-protein, vegan, or low-carb), especially in older adults, can significantly reduce the intake of vital nutrients, potentially leading to deficiency states. Below are some of the key concerns:

1. Accelerated Muscle Loss
Age-related muscle loss (sarcopenia) is a major concern in older adults. Low physical activity, combined with severely restricted calorie or protein intake, can accelerate muscle breakdown. This leads to reduced mobility, increased risk of falls and fractures, and ultimately, a loss of independence and quality of life.

2. Bone Health Risks
Excessively low-fat or low-dairy diets can accelerate the decline in bone mineral density due to inadequate vitamin D and calcium intake. Low-protein diets may also lack key nutrients essential for bone collagen formation – such as the amino acids lysine and proline, and vitamin C – thereby increasing the risk of osteoporosis and debilitating bone fractures.

3. Weakened Immune Function
Older adults naturally experience a decline in immune function, making them more susceptible to infections, cancer, and slower recovery from illness. Restrictive diets that limit essential nutrients – particularly zinc, vitamin C, vitamin E, and omega-3 fatty acids – can further impair immunity. Supplementation with these nutrients is often necessary.

A study published in the Journal of Cellular Medicine & Natural Health (W. Sumera et al., August 28, 2020) showed that a combination of vitamin C, vitamin E, zinc, selenium, B vitamins, and select plant compounds positively affected various aspects of immune cell function. Additionally, another study (W. Sumera et al., JCM&NH, July 25, 2024) found that a combination of vitamin C and the amino acid lysine showed beneficial effects against bacteria responsible for urinary tract infections.

Restrictive diets may also fail to provide the necessary nutrients and calories for proper healing, potentially increasing hospital stays, complicating recovery from illness or surgery, and delaying wound healing.

4. Cognitive Decline
Diets lacking in healthy fats (such as omega-3s), antioxidants, iron, vitamin C, and B vitamins can negatively impact cognitive abilities, including memory and concentration, and may increase the risk of developing dementia or Alzheimer’s disease.

Restrictive diets that eliminate entire food groups – and thereby deprive the body of important nutrients – may contribute to cognitive decline over time. Research has shown that specific combinations of nutrients, including coenzyme Q10, pyrroloquinoline quinone (PQQ), L-theanine, and plant compounds, can support brain function by increasing levels of Brain-Derived Neurotrophic Factor (BDNF), a protein essential for cognitive health, increase bioenergy production and protect brain cells against damage (Patent# US11304921B1).

5. Medication and Nutrient Interactions
Many older adults are on multiple medications (polypharmacy), which can interact with essential nutrients or be influenced by dietary restrictions. For example:

• Diuretics can deplete potassium and other electrolytes.
• Antibiotics can bind with calcium from dairy products, reducing absorption.
  
• Statins (cholesterol-lowering drugs) can reduce levels of coenzyme Q10, impairing cellular energy production.
  
• Antacids can reduce the absorption of vitamin B12 and essential minerals like calcium and magnesium.
  
• Blood thinners may require low-vitamin K diets, complicating nutritional balance.
  

Restrictive diets can further complicate medication management or reduce drug efficacy. It is important for older adults to consult with a healthcare professional before making significant dietary changes.

Conclusion

Dietary guidance for older adults should prioritize nutrient-dense, whole foods, with an emphasis on variety and balance rather than restriction. Meals should include adequate protein, sufficient fiber, healthy fats and ample fluid intake for proper hydration.

Restrictive diets in older adults should only be applied when medically necessary, as they carry significant limitations and risks – particularly when not supervised by a healthcare professional. The primary goal should be to support overall health, independence, and quality of life, rather than impose overly rigid or unnecessary dietary rules. Balanced, flexible, and enjoyable eating patterns are typically safer and more effective for managing weight and promoting healthy aging.