What Type of Intermittent Fasting is Safe for Seniors?

In many regions of the world, individuals 65 years and older represent a large and rapidly growing segment of the total population. Although life expectancy has substantially increased over the past century, rates of obesity and chronic disease are also on the rise among the aging population. In an effort to improve overall health and functioning, a growing body of evidence shows that intermittent fasting may positively improve several health outcomes associated with aging.

Key takeaways:

During the latter years of life, older adults experience several biological and metabolic changes that can greatly impair normal physical functioning. Factors such as excessive caloric intake and a sedentary lifestyle can speed up these changes resulting in functional decline and increased rates of disease.

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However, many individuals find it difficult to stick to diets that require caloric or nutrient restrictions. Instead of focusing solely on what and how much to eat, many older individuals are turning to intermittent fasting, which highlights the appropriate times of day to consume and abstain from food intake.

What is intermittent fasting?

Intermittent fasting can be defined as alternating periods of voluntary fasting and food consumption. The three most common types of intermittent fasting include:

  • Time-restricted eating (TRE). Only eating within a prescribed window of time each day and fasting for the remainder of the time. Examples of TRE include fasting for 16 hours with an eating window of 8 hours (16:8) or fasting for 14 hours with an eating window of 10 hours (14:10).
  • Alternate day fasting. Fasting every other day while only consuming 0-500 kilocalories on fasting days.
  • 5:2 diet. Five days of non-fasting and two non-consecutive days of fasting per week. On fasting days, caloric intake is restricted to 500–600 calories.

During periods of fasting that last longer than 12 hours, the body’s primary source of energy shifts from glucose to free fatty acids and fatty-acid-derived ketones. This means that the body switches from fat synthesis and storage to mobilizing fat out of adipose cells to be broken down for energy.

As a result, there is an increase in energy produced by the powerhouses of the cell – the mitochondria – and a reduction in reactive oxygen species that are linked to cellular damage and disease. Therefore, the energy source switch from glucose to fatty acids is believed to improve physical and cognitive function in older adults.

Can seniors fast for prolonged time periods?

Although there is increasing interest in intermittent fasting, research is lacking on the effects of prolonged periods of fasting (lasting two or more days) on the health of seniors. Most research conducted on older adults focuses on methods that do not exceed two consecutive days of fasting. In addition, the majority of the studies on fasting and older adults include small sample sizes and are short in duration (<12 weeks). Therefore, findings from these studies must be interpreted with caution, as the long-term effects of fasting in older populations are currently unknown.

Before adopting a fasting regimen, it is best to seek the guidance and supervision of a physician or registered dietitian. These healthcare professionals can advise you on the appropriate fasting protocol based on your medical history. There may be significant risks for seniors taking multiple medications and those with specific health conditions such as diabetes. Therefore, it is important to consider the risks and benefits, as outlined below.

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What fasting methods work better for seniors?

Current evidence suggests that one of the best forms of intermittent fasting for older adults is TRE, with daily eating periods ranging from 6 to 12 hours. Not only do seniors find it easy to adhere to TRE styles of intermittent fasting, but TRE is also considered a safe fasting approach for older populations with very few reports of adverse events.

An alternative form of TRE referred to as early time-restricted eating (eTRE), has also been shown to be effective in middle-aged and older adults. This form of TRE involves consuming all meals early in the day in order to follow the body’s natural circadian rhythm – also known as the internal biological clock.

Interestingly, the circadian rhythm regulates glucose, lipid, and energy metabolism. Aligning mealtimes with the circadian rhythm by consuming more food during breakfast and decreasing food intake later in the day has been shown to improve weight loss, lipid levels, and glycemic control – all while decreasing appetite. With this approach, food consumption generally occurs between 8:00–9:00 a.m. and 2:00–3:00 p.m. Therefore, eTRE is characterized by a 6-hour feeding period and an 18-hour fasting period (18:6).

What are the benefits?

Though the benefits of intermittent fasting have been documented extensively in young and middle-aged populations, current evidence on the effects of fasting in seniors is limited. Nonetheless, the small studies that have been conducted have shown that intermittent fasting may result in:

  • Weight loss accompanied by reduced body fat
  • Reductions in diastolic and systolic blood pressure
  • Improved insulin sensitivity
  • Reduced oxidative stress
  • Induced autophagy
  • Lowered levels of IGF-1
  • Reduced Appetite
  • Improvements in quality of life
  • Decreased fatigue
  • Increased walking speed revealing improved exercise capacity

What are the risks?

While intermittent fasting is generally considered safe for most individuals, there are several risks that older adults should be aware of.

Lean muscle mass loss

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One significant risk of TRE for seniors is the potential loss of lean muscle mass. This is particularly alarming because older adults are at higher risk of the age-related loss of skeletal muscle mass and strength, known as sarcopenia. Therefore, it is imperative that seniors consume adequate amounts of protein during designated eating windows while adhering to fasting regimens.

Hypoglycemia

Another potential risk of intermittent fasting is hypoglycemia – especially among seniors with type 2 diabetes. Specifically, the 5:2 diet has been shown to induce incidents of low blood sugar. Therefore, talking to your doctor before adopting this dietary protocol is crucial.

Interference with prescription drug use

Older populations are also more likely to be on several prescription medications that need to be ingested with food. Therefore, intermittent fasting can interfere with proper prescription drug use.

Potential adverse reactions

Other adverse reactions to intermittent fasting include headaches and nausea. For these reasons, it is important to ensure that you are consuming adequate amounts of fluids (in the form of water, coffee, or tea) during fasting periods, along with a well-balanced, nutrient-rich diet during non-fasting periods to prevent unwanted symptoms.

Given the risks and benefits, intermittent fasting – adopted under the strict supervision of a healthcare professional – may impart positive metabolic shifts that improve weight management, blood pressure, insulin sensitivity, and quality of life among seniors. However, future studies need to be conducted to assess the effects of intermittent fasting in the older population using larger sample sizes over longer periods of time.

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