2 Types of Fasting for Weight Loss and Brain Boosts

Note: before commencing any fasting regimen, please consult with your doctor or health professional.

During the past several years, fasting has become extremely popular, and for good reason. Done correctly, this ancient practice can help you shed those extra pounds, boost your metabolism, and optimize your brain health.

Intermittent Fasting (IF) is a well-known, scientifically-sound approach to fasting. Less known, but equally effective is early time-restricted fasting (eTRF). This article will familiarize you with both, so you can decide which might be better for you.

Briefly put, IF involves restricting your daily food consumption to a 6- to 8-hour window. For most people, this amounts to skipping breakfast, then eating lunch and an early dinner (no late-night snacking!).

With eTRF, we push that window earlier, so you consume all your food before 2pm – or preferably 12pm – depending how early you wake up. Both these fasting practices have amazing benefits, particularly regarding weight loss, but research suggests eTRF might be more beneficial. Let’s look at some IF studies, to see what eTRF is up against.

A 2019 meta-analysis, comprising pooled data from 12 IF studies, demonstrated significant weight loss, plus greatly improved blood glucose and insulin levels for IF, as compared to a control diet. A similar review showed that IF, when maintained for 1-6 months, promotes up to 8% weight loss and a 7% waist circumference reduction. Can eTRF top this?

The Rising Star of the Fasting World: eTRF

Interest in eTRF has been growing tremendously within the scientific community during the past several years. Until recently, however, eTRF studies had only been conducted on rodents. Then, at the 2016 annual meeting of the Obesity Society, Dr. Courtney Peterson and her University of Alabama colleagues discussed the first-ever eTRF experiment on humans.

Their research, which at that time was preliminary and unpublished, showed eTRF can significantly improve weight loss, not by increasing calorie burning directly, but by reducing daily hunger swings. In effect, eTRF harmonizes your meals with your circadian rhythms (your body’s internal clock). This promotes homeostasis, which curbs food cravings while improving fat-burning efficiency during sleep.

Dr. Peterson and her colleagues published their groundbreaking research in 2019 in the renowned journal, Obesity. Peterson commented, “We suspect that a majority of people may find meal timing strategies helpful for losing weight or to maintain their weight since these strategies naturally appear to curb appetite, which may help people eat less.”

The top benefits of eTRF include:

  • Reduced cravings and less hunger swings
  • Improved fat-burning efficiency, especially during sleep
  • Improved metabolic flexibility (the ability to utilize both carbs and fat for energy)
  • Potential for significant weight loss
  • Potential to increase autophagy and have anti-aging effects

Research on eTRF is still in its early years, but the evidence suggests it’s as effective, if not more effective, than IF for weight loss and a broad range of metabolic improvements. Whether you choose to skip lunch and dinner (eTRF), or skip breakfast (IF), you’ll be improving your health either way.

Let’s now examine a few nutritional molecules that can supercharge your fasting, before looking into the science of IF.

Nutritional Molecules that Improve Fasting

Fasting, by definition, implies limitations on daily food intake. With this in mind, the food and nutrients you actually consume become even more important. You can boost your fasting results by supplementing with certain nutrients. The ones I recommend most include:

Green Tea Extract – a potent source of antioxidants (which reduces oxidative stress) and catechins (which increase calorie burning via thermogenesis).

Naringin – a grapefruit-derived flavonoid that improves fat oxidation while promoting visceral fat reduction.

L-Carnitine – an amino acid that burns fat while also improving brain function and aiding in disease prevention.

Creatine – an amino acid complex that decreases body fat by promoting lean muscle mass development.

Forskolin – a root-plant that balances hormones while increasing lipase, an enzyme responsible for metabolizing fat.

Some of these molecules are obtainable through food, but nutritional supplements are purer, more potent, and more effective. Click on any of the molecules above to learn more.

The Science of IF

The benefits of IF come from restricting your entire day’s food consumption into a 6- to 8-hour window. In simpler terms, this means eating just 2 meals per day (skipping either breakfast or dinner). You’ll derive greater benefits from multiple, consecutive days of IF, but even one day per week is beneficial. IF promotes weight loss plus an array of other benefits, including:

  • Improved insulin resistance
  • Reduced oxidative stress,
  • Reduced inflammation,
  • Improved learning and memory functioning
  • Improved heart health
  • Improved brain health,
  • Enhanced cognitive function
  • Reduced onset and/or severity of Alzheimer’s disease
  • Possible cancer suppression
  • Possible anti-aging and prolonged lifespan,

Below, we’ll examine brain-health benefits in greater detail, but first let’s understand why IF and other fasting practices have such profound effects. 

How it Works: Cell Stress

During periods of fasting, cells experience a beneficial kind of stress. According to Dr. Mark Mattson, one of the world’s leading IF experts, this stress triggers an adaptive response, which enhances the body’s stress-coping abilities and its ability to resist disease.

At the cellular level, the stress of fasting is similar to that exercise. In other words, both are beneficial kinds of short-term stress that empower our cells to become stronger and more adaptive. Everyone knows exercise is healthy, but how many realize fasting has similar benefits?

How it Works: Caloric Restriction

Reducing calories, while maintaining adequate nutrition, is among the most-studied, surest strategies for preventing disease and prolonging lifespan. For example, a study examining the impact of IF on prostate cancer concluded, “Caloric restriction, undernutrition without malnutrition, is the only experimental approach consistently shown to prolong survival in animal models.”

Despite these benefits, most people don’t want to spend their entire lives on calorie-restricted diets. Luckily, we don’t have to – IF performs similar to prolonged caloric restriction with respect to weight loss and insulin sensitivity. This is great news because implementing IF is easy, practical, and enjoyable, unlike prolonged caloric restriction.

How it Works: Burning Fat as Fuel

When you eat carbs, your liver converts them into glycogen, which it stores for energy. When you then stop eating carbs, then you deplete your glycogen stores within 10 to 12 hours. Therefore, if you’re eating 3 meals per day inclusive of carbs, you always have glycogen stored in your liver for energy.

Whenever glycogen is available, your body always utilizes it for energy. What happens though when glycogen becomes depleted? In this case, the body switches to burning fat for energy. Via a process called ketosis, your liver metabolizes fatty acids, thereby creating ketone bodies. These ketone bodies are an alternate fuel source and an excellent one at that. In fact, brain cells burn ketone bodies even more efficiently than glucose.,

While practicing IF, you of course are not eating for 16 to 18 hours each day. For most people, this is enough time to deplete glycogen stores, especially people on low-carb diets. Therefore, IF facilitates ketone body production, which in turn helps you burn more fat.

How Does IF Improve Brain Health?

As you know, when you refrain from exercise, your muscles get smaller and weaker. When you exercise regularly, your muscles get larger and stronger. The brain is the same way. The brain needs its own form of exercise, things like analytical challenges and brain games.

When the brain has such challenges, it boosts production of proteins called neurotrophic factors. These include FGF and BDNF. The increase of neurotrophic factors leads to the growth of new neurons and the formation and maintenance of brain synapses, which improve memory, learning, and other cognitive abilities.

Besides brain games, guess what else increases neurotrophic factors? That’s right, fasting. Specifically, IF increases BDNF, which protects brain neurons against dysfunction and degeneration. As you can see fasting, including both IF and eTRF, has health benefits far beyond just weight loss.


Fasting is a time-tested tradition, which is supported by ancestral wisdom as well as modern scientific research. That being said, you should still consult with your doctor or trained health professional before starting any fasting program.

People who are in weakened and or fragile conditions might experience unwanted, potentially dangerous side effects from fasting. This includes anyone with a chronic disease, such as heart disease, diabetes, metabolic disease, etc. To be clear, fasting may indeed benefit these people, but the approval and guidance of a trained doctor is critical.

Pregnant women should also refrain from fasting for many reasons, particularly because the growing baby needs all the nutrients that he/she can acquire. Please speak with your doctor and share this article with him or her before you start fasting, even if you are already in excellent health.

IF or eTRF? To Breakfast or Not to Breakfast?

As we have discussed in this article, the scientific literature overwhelmingly supports daily fasting, meaning limiting your food consumption to a 6- to 8-hour window, whether it be IF of eTRF. The benefits include weight loss, improved metabolism, anti-aging, improved brain health, and much more. But does it matter when during the day you schedule your 6- to 8-hour window?

Both IF and eTRF have major benefits. Emerging science, however, suggests eTRF provides more benefits. This is because eTRF aligns food consumption with circadian rhythms, which decreases food cravings while promoting deep, restful sleep. The sooner you finish your last meal of the day, the more efficiently your body can manage cell repair, cell regeneration, and its other sleep-time jobs.

To conclude, IF is easier and more practical, but eTRF is slightly more effective. Just one day per week of either IF or eTRF will improve your health. Take it slow, but if you feel great, gradually increase to more days per week. Let me know how it goes for you. I’m sure you’ll be happy with the results.


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