Calorie Restriction and Intermittent Fasting: Eating Your Way to a Healthy, Long Life

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JUL 15, 2020

Arguably, the two most current and popularized diets are calorie restriction and intermittent fasting. Although often confused, they’re vastly different in terms of application and effects.

For intermittent fasting, you eat what and how you like but within a set timeframe. Some of these plans, amongst others, could be:[1]

• The 5:2 pattern: eating as you like for five days a week, but only consuming 500-600 calories per day for the other two days
• The 16/8 pattern: eating for a defined eight-hour window of time each day, but fasting for the remaining 16 hours
• The Warrior Method: also considered a 20/4 pattern, this involves fasting for 20 hours and eating in a defined four-hour window at night
• Alternate Day Fasting: a full day of consuming any food or drink you want with no limitations, followed by a 24-hour fasting period, on repeat
• No plan! - Spontaneous Fasting: not all intermittent fasting plans are premeditated, and deciding on a whim to skip a meal when you’re not hungry can also fall under this category

Calorie restriction (CR), on the other hand, is about actively reducing your calorie intake whenever you eat. Rather than place timetable limitations, this method limits the amount of calories consumed at regular meal times.

• Low in calories, high in nutrition: A key aspect of calorie restriction is to maintain proper nutrition despite consuming fewer calories. This is primarily accomplished through the consumption of fruits and vegetables.
• Anytime, anyday: Unlike fasting or a “starvation diet”, calorie restriction actively reduces intake at all times of consumption without limiting the time allotted for eating.
• Benefits maximized: Calorie restriction does not selectively target the intake of macronutrients, such as proteins or carbohydrates, but instead serves to maximize the benefits of each one in a reduced, healthy quantity.

Turns out even the bagel you eat for breakfast or the pasta for dinner has an impact rooted in biology — the science of eating explains why calorie restriction and intermittent fasting can positively impact your health.

Though your intake may be limited by time, intermittent fasting offers a multitude of consistent benefits.

Have you ever wondered how your body naturally rises in the morning, feels hungry in regular intervals, and is ready for bed at a consistent time each day? You can thank your body’s natural clock, found in the suprachiasmatic nuclei (SCN), for that. The SCN and our natural 24-hour circadian rhythms are not only responsible for that predictable routine, but also for the scheduled release of hormones and coordination of metabolic processes.

For this reason, consuming foods at the same time intervals, as is done in a few intermittent fasting routines, has been found to streamline metabolism. When followed for an extended period of time, the body slowly becomes more accustomed to maximizing food processing at those times, and is able to better allocate resources throughout the day. This not only reduces your risk of obesity and cardiovascular disease, but can also aid in energy balance that contributes to longevity.[2]

We all know that bad bacteria can lead to disease and infection, but did you know that there are naturally existing “good” bacteria in our bodies that actually facilitate digestion and contribute to our health in a big way? In fact, it has been discovered that the composition of gut microorganisms varies significantly between those who are overweight and those who maintain a healthy weight range, pointing to the critical role that your microbiome can play in weight management and health. It turns out that intermittent fasting can prevent changes to gastrointestinal microbiota that would otherwise increase systemic inflammation and glucose intolerance, allowing your gut bacteria to help aid in weight management.[3]

Directly after a meal, the body’s preferred fuel option is glucose and other carbohydrates from the nutrients in that meal. Any simple sugars that are not used as an immediate source of energy are converted into glycogen, which is a long-term storage form for carbohydrates. The hormone insulin is responsible for creating these storage compounds, while the hormone glucagon is responsible for breaking them down when the body needs energy again. When you eat consistently throughout the day (i.e. don’t fast), your body will have a consistent source of glucose or glycogen to turn to for energy, and will not be compelled to use any other energy source in the body.

However, with intermittent fasting, such as alternate day feeding or the 16/8 pattern, your stores of glucose and glycogen become depleted without any food to replenish supplies. As a result, intermittent fasters will see their bodies resort to its fat stores for energy in a process termed the “metabolic switch”. This is one of the mechanisms by which intermittent fasting can result in healthy weight loss.[4]

One of the hallmarks of aging is the accumulation of old, damaged cells and failure of our body’s natural mechanisms to replace these. Studies have shown that our cellular repair mechanisms are actually more active during periods of fasting than they are during periods of feeding. During these times, our cells are able to identify and digest old proteins and molecules that are obstructing cellular function in the same way a buildup of rust would impair a bike.[5]

Even beyond the expected impacts of limiting food consumption to one or a few time windows, intermittent fasting can also benefit various lifestyle factors. For example, by helping to maintain a healthy circadian rhythm, intermittent fasting has been found to regulate sleep cycles. Furthermore, contrary to popular belief, intermittent fasting does not encourage overeating during feeding windows, and can help create healthy habits with food choices.[6]

While intermittent fasting offers many health benefits, if it doesn’t sound like your cup of tea, calorie restriction in a healthy diet has been scientifically proven to positively impact metabolism, longevity, and overall health in a similar way to intermittent fasting and can be just as effective for weight management.

OneFact 3,500 calories equals about 1 pound of fat! So how does calorie restriction accomplish these metabolic tasks? The key lies in the cellular response to feeding. After eating, your body naturally mobilizes insulin and leptin – the hormones that, respectively, convert food into energy and monitor satiety (the feeling of being full) and maintain a healthy level of body fat. A larger, unrestricted meal will increase blood insulin and leptin more than a smaller, restricted meal. This is due to the larger amounts of carbohydrates that need to be processed. While these hormones are necessary for proper energy sequestration, chronic elevation following prolonged consumption of unrestricted meals can actually contribute to cardiovascular disease and Type 2 diabetes.[7] This is because overproduction of insulin causes cells to absorb more glucose, and any extra glucose that remains is converted into fat.[8]

The exciting news is, yes, it can. With unrestricted eating habits, aging populations experience a rapid accumulation of senescent cells. But caloric restriction can lessen these age-related changes by limiting the recruitment of insulin and leptin and targeting regulatory pathways that respond to a low-energy state. Even better, by ameliorating metabolic health and reducing the risk of disease, calorie restriction has been proven to prolong the lifespan of rodents and other animal models.[9] In the case of calories, less is absolutely more!

Other studies found that a reduced caloric intake in mice diminished damage to DNA, which consequently minimized cellular senescence.[10],[11] And since senescent cells impact surrounding cells like a rotten apple in a basket, if the signals that cause senescence are reduced, then calorie restriction directly alleviates the accelerated onset of the hallmarks of aging and contributes to a longer, healthier life.

Faced with all of this scientific evidence, the question remains — how can I implement intermittent fasting or calorie restriction into my daily routine? Perhaps one of the most appealing aspects of both is their emphasis on reforming rather than revolutionizing your diet. This allows you to continue to eat the healthy foods you love while reducing quantity when there’s no longer a health benefit.

At the same time, each of us is unique and everyone responds differently to a calorie restricted diet. According to dieticians and health professionals, the first step to determining what might work best for you is to get a baseline level of your blood glucose and cholesterol through blood tests. This can be a very helpful way to monitor your progress and to formulate your own individual dietary plan with a professional.

Though the same plan may not work for every individual, there are some general guidelines that professionals say should be incorporated into any healthy lifestyle, regardless of whether you’re partaking in intermittent fasting or calorie restriction:

• Go Four for Four:[12],[13]
• Fruits: Not only are fruits low in calories, but they can also provide natural sugars, fiber, and vitamins for a quick energy boost. While an apple a day is known to keep the doctor away, any fruit can be incorporated into your healthy diet, from apricots and peaches to plums and pears.
• Vegetables: Not only are vegetables overflowing with nutritious value, they are also low-calorie additions to any diet. While baby carrots have often been heralded as one of the healthiest snacks, broccoli, cauliflower, and beans are also making their name in healthy diets. Add that in with some leafy greens, and you have yourself a fulfilling meal or snack.
• Grains: Incorporating grains into your diet has been found to maximize nutrient intake without a high caloric burden. Grains are also great sources of antioxidants, which are effective at neutralizing the build-up of toxic molecules within skin cells. Look for foods made with wheat, rice, or oats to meet this quota in your meals. Excellent options for a filling yet calorically conservative diet include whole grain pasta, wheat bread, and rice.[14]
• Proteins: In addition to helping us build and maintain muscle, proteins are a key component of nearly every structural and regulatory component in our bodies. Lean protein also plays a key role in boosting immune health and increasing our body’s rate of metabolism. In fact, a high-protein diet can even reduce your cravings, since proteins take a longer time to be broken down and therefore make you feel full for more time.[15] This makes dietary proteins one of the most important ingredients in a meal. Lean protein can be found in chicken breast and most seafood, and can be bolstered by vegetarian options such as lentils, tofu, and Greek yogurt.
• Hydrate, hydrate, hydrate!: Water is a universally important component, and for good reason too. Adequate hydration is necessary for proper functioning of every organ in the body, and is one of the best known ways of maintaining youthful skin. Water consumption is also linked with a healthier variety of gut microbiota as well as healthier glucose regulation.[16] For intermittent fasting, water can be consumed even outside of feeding windows; for calorie restriction, it can be a great way of washing down each of those nutritious meals.[17]
• Extend the Benefits with Exercise: The benefits of calorie restriction and intermittent fasting, particularly in preventing the onset of age-related cellular damage, are enormous — and easily attainable with healthier choices! By combining a healthy diet with exercise, you can exert a stronger grasp on your own health and reduce your susceptibility to disease.

• Wash the dust off of the cutting board, and slice up some carrots and cucumbers paired with a low-calorie dip for a healthy, low-calorie snack.

References

• [1] https://www.healthline.com/nutrition/6-ways-to-do-intermittent-fasting#TOC_TITLE_HDR_7
• [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4516560/
• [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4516560/
• [4] https://www.hopkinsmedicine.org/health/wellness-and-prevention/intermittent-fasting-what-is-it-and-how-does-it-work
• [5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106288/
• [6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4516560/
• [7] https://www.nature.com/articles/nrm1616
• [8] https://www.mayoclinic.org/diseases-conditions/diabetes/in-depth/insulin-and-weight-gain/art-20047836
• [9] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014770/
• [10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2984605/
• [11] https://jamanetwork.com/journals/jama/article-abstract/1108368
• [12] https://health.gov/sites/default/files/2019-10/DGA_Healthy-Eating-Pattern.pdf
• [13] https://health.usnews.com/wellness/food/articles/intermittent-fasting-foods-to-eat-and-avoid
• [14] https://www.myplate.gov/eat-healthy/grains
• [15] https://chwbonline.com/top-10-health-benefits-lean-protein/
• [16] https://www.nature.com/articles/s41598-018-34761-5
• [17] https://greatist.com/eat/what-to-eat-on-an-intermittent-fasting-diet