How Often Should You Eat?

Dr. Al Danenberg Nutritional Periodontist

October 11, 2020 [printfriendly]



Should you eat every 3-5 hours? Should you eat only when you’re hungry? Should you eat as soon as you wake? And should you eat just before going to bed?


What about fasting?


Lots of questions. Certainly, there are lots of opinions. But is there science-based research that can offer some insight and direction?


The answer is, “Yes, there is science.” Let’s get into it.



Published Medical Review

For most people, eating frequently is not healthy. Eating shortly before going to bed is not good for the digestive system. In fact, medical research shows “not eating” for long stretches of time during a 24-hour day is beneficial. Eating within a specific time window over the course of the day is considered intermittent fasting. This is my focus in this article.


The New England Journal of Medicine published an in-depth review of intermittent fasting in its December 16, 2019 edition. Eighty medical, peer-reviewed papers were cited in this article to substantiate its claims. This is one of the most inclusive medical papers supporting the fact that intermittent fasting is healthy. It is the way our primal ancestors survived and thrived, and it is the path to overall wellness.


Intermittent fasting is safe for the far majority of people. But it is safe only if you eat a nutrient-dense, anti-inflammatory diet. If you are eating a “standard American diet” consisting of high carbohydrates, added sugars, unhealthy fats, and devoid of other necessary nutrients, then intermittent fasting as well as any other frequency of eating is not healthy.


For example, a medical study published on 9/22/20 summarized that intermittent fasting did not significantly cause weight loss compared to its control group. In fact, the study also showed that there was a loss of muscle mass in the experimental group. However, the study participants did not eat a nutrient-dense, anti-inflammatory diet that I believe is critical for intermittent fasting to be effective and healthy. Actually, the authors of the study write about these limitations in their Conclusion at the end of their paper.



Summary of Benefits of Intermittent Fasting:

  • Improves blood glucose fluctuations
  • Strengthens the immune system
  • Reduces the risk of metabolic diseases
  • Helps create metabolic flexibility
  • Increases fat metabolism
  • Contributes to weight loss
  • Cleanses the body by causing weak cells to die or renew themselves
  • Assists in preventing Alzheimer’s Disease
  • Extends life expectancy


Our primal ancestors never consumed three meals a day. And in-between snacks were not their “M.O.” How absurd is the notion that primitive man ate on a schedule? Humans always have eaten when they were hungry and drank when they were thirsty. Frequently, they could not find food. They had to fast until the next meal was secured. But their metabolism was capable of utilizing stored fat in their body to provide the fuel to function. There is no such thing as a time to eat breakfast, lunch, and dinner.



Intermittent Fasting (Time Restricted Eating)

The most popular and efficient method of restricted eating is not eating for 16 to 20 hours at a time. In other words, you only eat within the window of 4-8 hours and fast the remaining 16-20 hours of a 24-hour day. As an example, you might finish your last meal of the day by 8 PM and then not have any food to eat until the next day between noon and 4 PM.


There are other methods of restricted eating. Two approaches are:

  • Alternate-day fasting. Eat a normal diet one day and fast the next day.
  • 5:2 fasting. Eat a normal diet for five consecutive days a week and fast the other two days of the week.


After one stops eating for 12-18 hours, liver glycogen (stored glucose) becomes depleted. Then, lipolysis can become a major energy pathway, producing energy from body fat if additional carbohydrates are not consumed. Triglycerides in fat cells begin to break down into glycerol and free fatty acids.[1] The free fatty acids that travel to the liver can be converted into ketones. Ketones are easily used by the body’s cells to burn as fuel.


During the fasting stage, insulin levels are low. With low insulin, damaged cells are encouraged to repair themselves and clean themselves out. This is called autophagy. When damaged cells are beyond repair, they could trigger themselves to commit suicide. This is called apoptosis.



However, you should consult with your medical doctor before trying intermittent fasting if you …

  • Have diabetes
  • Have problems with blood sugar regulation
  • Have low blood pressure
  • Take medications
  • Are underweight
  • Have a history of eating disorders
  • Are a woman who is trying to conceive
  • Are a woman with a history of amenorrhea
  • Are pregnant or breastfeeding




Here are specific benefits of fasting which are reported in various published peer-reviewed papers. Most are from animal studies, but a few are with human participants.



Affects Cells and Hormones

Insulin levels drop during fasting periods, which allows fats cells to release their stored fat as fuel.[2] At the same time, human growth hormone increases as much as five times its normal level. Higher growth hormone assists in fat burning and muscle development.[3] Also, cells begin to repair themselves by removing accumulated waste material.[4],[5] Other benefits include improved longevity and protection against disease. [6],[7]


Regular switching between burning fat for fuel and burning carbohydrates for fuel promotes long-term maintenance of a variety of organ systems, disease resistance, and improved performance.[8] The ability for the body to switch back and forth efficiently and effectively between fuel sources is called metabolic flexibility.[9]


A clinical study of 1422 participants clearly showed significant health benefits from various types of fasting.[10]


Reduces body Weight and Belly Fat

When you fast, you eat fewer meals. Fewer meals mean fewer calories. Serum glucose declines, norepinephrine increases, and the metabolic rate increases, which burns more calories. The result is weight loss as well as loss of belly fat.[11],[12]


Improves Insulin Sensitivity and Type 2 Diabetes

Insulin sensitivity is when the body reacts to normal insulin production by the pancreas. However, when the body’s cells fail to respond to normal levels of insulin, it is called insulin resistance. Insulin resistance causes an increase in blood sugar and the development of type 2 diabetes. But fasting improves insulin sensitivity and can protect against type 2 diabetes. In a small study of three patients, intermittent fasting reversed their type 2 diabetes.[13]


Lowers Oxidative Stress and Systemic Inflammation

Oxidative stress is when unstable molecules (called free radicals) damage important molecules like protein and DNA.[14] Medical studies show that intermittent fasting helps the body to neutralize excessive free radicals and reduce inflammation.[15],[16],[17]


Decreases the Risk of Cardiovascular Disease

Intermittent fasting has been shown to improve different risk factors for cardiovascular disease. Specifically, it lowers blood pressure, total and LDL cholesterol, blood triglycerides, inflammatory markers and blood sugar levels.[18]


Assists in Cancer Prevention and Cancer Treatment

Cancer is characterized by uncontrolled growth of cells. Various animal studies have shown that caloric restriction can prevent cancer. In addition, human studies also have suggested that intermittent fasting could improve outcomes with conventional cancer treatment.[19]


May Improve Brain Health

Fasting improves metabolism and optimizes brain cell growth in a way that may counteract a broad array of neurological disorders. In animal studies, fasting improves cognition, stalls age-related cognitive decline, slows neurodegeneration, enhances functional recovery after stroke, and lowers the pathological and clinical features of epilepsy and multiple sclerosis (MS).[20] Here is a study, which is the first clinical trial investigating the effects of a ketogenic diet and fasting on disease progression in MS patients.


Helps to Prevent Alzheimer’s Disease

Alzheimer’s disease is the world’s most common neurodegenerative disease, and there is no cure today. But in a recent animal study, intermittent fasting prevented memory decline.[21] Also, animal studies have shown that intermittent fasting may improve Alzheimer’s disease though the process of autophagy.[22]



My Personal Path

The research I have cited clearly shows that fasting improves overall health. But the choice of foods must be nutrient-dense and anti-inflammatory. However, it is important for some individuals with underlying medical conditions to check with their medical practitioners before starting any fasting program.


I incorporate intermittent fasting in my Unconventional Cancer Protocols. Up until recently, my last meal of the day ended about 7 PM. I usually went to sleep around 9:30 PM and woke around 5:30 AM. Generally, I ate my first meal of the day around 2 PM. That’s about the time I got hungry. But now I have made some changes.


I follow my Better Belly Blueprint (my way of eating). My diet is a relatively strict animal-based way of eating with less than 20 grams of carbs. I eat this way for 6 continuous days. But now, I may not eat my first meal until 4-5 PM. And on those days, I might feel satiated from eating that one meal and won’t eat again until the next day.


Then on the 7th day, I cycle out of my ketogenic diet and eat about 100 – 150 grams of carbohydrates and reduce my fat intake to encourage metabolic flexibility. On this 7th day, I select my carbs from raw honey, bee bread, and a few fruits and vegetables that are low in phytates, lectins, and oxalates.


From the medical trials and published articles I have read, intermittent fasting might be the healthiest path to a robust immune system, quality of life, and longevity. Cycling in and out of a ketogenic way of eating will keep me metabolically flexible. But it is vital that the foods I consume (and that you consume) must be nutrient-dense and anti-inflammatory.


An excellent book that describes the benefits of ketones, cycling in and out of keto, and metabolic flexibility is Ketones: The Fourth Fuel by Travis Christofferson. I think you’ll enjoy Travis’s way of writing. It reads like a novel but is packed full of great science. Also, Carnivore Aurelius is an excellent resource to dive into more information about the animal-based diet.


























Check out my new training on the Better Belly Blueprint! You can watch it HERE.


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1 Comment

  1. I am currently doing a carnivore diet. Moderate protein and high fat. I do intermittent fasting. Have done it for 2 years. Have been doing carnivore for 10 months. However my tryglecerides have gone from 35 on a SAD diet to 144 on carnivore with saturated fat. I only eat meat, fat and water. I am concerned. I don’t understand why. I am in deep ketosis because I need to heal many issues including amenorrhea. My insulin is 1.2 and CRP is .5 but my tryglecerides just keep creeping. I have tested them 4 times, after 12,14 and hours fasted.

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