“Reverse Prediabetes?” Two Scientist Show How To Do It (and one does)

reverse prediabetes

The reason you need to know how to reverse prediabetes is because there’s a good chance that you’re prediabetic. New research shows that time-restricted feeding improves insulin, blood pressure and oxidative stress biomarkers, leading to a healthier, and perhaps longer life.

reverse prediabetes

Credit: Harvard Health Publishing (www.health.harvard.edu)

Intermittent Fasting (IF) has become the rage. This is unsurprising, given that it can help reverse prediabetes, and that many research studies attest to its overall health benefits, which nicely squares with the experience of many of us who have tried it.

The pertinent question is:

Is it worth it?

We resist change. Any form of IF requires a big change and commitment. You need a big incentive. And you’re about to get one, two… a few, actually.

Here’s what we’re going to cover in this post:

  • The many benefits of Intermittent Fasting
  • Why your blood sugar numbers are probably scary
  • How to reverse prediabetes by Time Restricted Feeding
  • Reverse prediabetes by eating earlier

Let’s dig in…


The Many Benefits of Intermittent Fasting


reverse prediabetes

Dissect the word and you get a sense of what Intermittent Fasting means: you don’t eat on an intermittent basis. Over some period you eat. Over another slot of time you don’t. The on/off cycle could occur during a 24 hour period, every other day, two days of seven, one week of a month, etc.

Some of the reputed physical benefits of fasting include: (1)

  • Improved mental clarity and concentration
  • Weight and body fat loss
  • Lowered blood insulin and sugar levels
  • Reversal of type 2 diabetes
  • Increased energy
  • Improved fat burning
  • Increased growth hormone
  • Lowered blood cholesterol
  • Prevention of Alzheimer’s disease (potential)
  • Longer life (potential)
  • Activation of cellular cleansing (potential) by stimulating autophagy (a discovery that was awarded the 2016 Nobel Prize in medicine)
  • Reduction of inflammation

But what form of IF are we talking about?

As mentioned, fasting strategies can take many forms. Three popular IF protocols you may have heard about are:

(Read: Choose Your Favorite Intermittent Fasting Protocol (and watch the fat melt away).

Among all forms of IF, the so-called “Time-restricted feeding” (TRF) may be the most intuitive and easily done. With TRF you simply compress the time you eat within a shorter than usual time window, say from four to ten hours.

Compare that to the time range within which you typically are consuming food or drink.

Most of us begin our day with at least a cup of coffee or tea as soon as we arise, and don’t stop consuming something till near bed time. If you arise at 7:00 AM and go to bed at 10:00 PM, you may be putting something in your mouth over a stretch of 14 hours, not four to ten hours.

So what?

Well, whether that matters to you depends on what health outcome you want. Recent studies on TRF report positive effects on weight loss, glycemic control and appetite regulation. Improvements in body composition are clearly helpful for metabolic health, especially in those people who are already prediabetic.

But you’re not prediabetic, you say?

Are you sure about that?


A Look At the (Scary) Numbers

WebMD reports that about 86 million Americans are prediabetic, meaning that their blood sugar level is higher than it should be, but not yet in the diabetes range. The CDC reports that more than 100 million Americans have prediabetes and diabetes. Given a population of around 320 million, that means that just below one of every three Americans have a sugar/insulin resistance problem, and it’s not going away.

For both people in the U.S. and the rest of the world, the prevalence of prediabetes is increasing. Experts have projected that more than 470 million people will have prediabetes throughout the world by 2030. (2)

Let’s take a look at some sugar numbers as presented by WebMD and the Life Extension Foundation (LEF).

WebMD defines normal, prediabetes and diabetes using a general reference range representing the U.S. population; these are numbers your doctor would most likely adhere to.

Fasting plasma glucose test:

  • Normal if your blood sugar is less than 100
  • Prediabetes if your blood sugar is 100-125
  • Diabetes if your blood sugar is 126 or higher

Hemoglobin A1C (or average blood sugar) test:

  • Normal: 5.6% or less
  • Prediabetes: 5.7 to 6.4%
  • Diabetes: 6.5% or above

Based on its review of the pertinent research, The Life Extension Foundation thinks that the above blood sugar/glucose categorizations for normal, prediabetes and diabetes advocated by WedMD are too lenient. LEF says that your risk for age-related chronic disease is far greater at these “normal levels” than has been previously recognized, and put the ideal fasting glucose should range between 70 and 85 mg/dL (3.9 – 4.7 mmol/L). (Go here for blood glucose conversion table.)

One team of researchers found that the risk of developing diabetes itself was increased more than seven-fold in people with fasting glucose levels of 105-109 mg/dL, compared with people with fasting glucose levels less than 85 mg/dL, says LEF, and point to the following risks associated with “normal” blood sugar levels:

Increased Health Risks in People with “Normal” Glucose Levels (3)
Condition Glucose Levels (mg/dL) Increased Risk
Developing Type 2 Diabetes 100-104 Up to 283%
Stomach Cancer 95-105 Up to 130%
First-time Heart Attack Above 88 242%
Need for Coronary Bypass or Stent Procedure Above 95 73%

If you accept LEF’s summary of the research attesting that 85 mg/dL is the high mark of acceptable fasting glucose, then I’d be willing to bet that yours is unacceptable for optimum health. (By the way, often times mine is too, as I elaborate in the article, You Absolutely Need To Lower Your Blood Sugar, Part 1 — The Five Symptoms.)

Which brings us to an eye-opening new study published in Cell Metabolism reviewed by Scripps Research Institute scientist, Dr. Drew Duglan.


Reverse Prediabetes Via Time Restricted Feeding

Dr. Duglan reports that you can reverse prediabetes and diabetes as well by restricting the time window in which you eat, particularly if you do so earlier in the day to match your circadian rhythms.

reverse prediabetes

Dr. Drew Duglan

He comes to this assessment through his review of new, rigorous, 5-week randomized crossover feeding trial on eight prediabetic men conducted by scientists at the University of Alabama, Birmingham. The rest of this review of the study relies on Dr. Duglan’s interpretation.

The participants were asked to adopt one of two eating schedules:

  1. Early Time Restricted Feeding (eTRF) schedule consisting of a 6-hour eating window, wherein the last meal was consumed before 3:00 PM each day, or
  2. A 12-hour eating schedule.

After a seven week break, each participant switched over to the other schedule.

reverse prediabetes

The researchers wanted to gauge whether intermittent fasting has benefits independent of weight loss. Therefore, food intake and meal composition was matched across both eating schedules, and each participant was fed enough food to prevent any reductions in body weight.

Compared to participants on the 12-hour schedule, those on eTRF experienced four important biomarker improvements (the first two pointing to both insulin sensitivity and β-cell responsiveness):

  • A decreased fasting insulin,
  • A decreased level of insulin during an oral glucose tolerance test,
  • A significant decline in systolic and diastolic blood pressure equal to  anti-hypertensive medications, and
  • Reduce levels of 8-isoprostane, a marker of oxidative stress.

Now remember that these improvements for those in the eTRF group were compared to those eating for 12 hours and fasting for 12 hours (about eight of those sleeping). Imagine the more striking benefits if compared to how most of us eat and drink, which is well beyond 12 hours of every 24 hour cycle.

What about hunger?

A common critique of most TRF protocols is the assumed increase in hunger during the longer fasting periods. Let’s face it, if you’re hungry all the time, you won’t do it. In this study, however, participants on the eTRF schedule scored lower on most subjective measures of evening appetite, such as the desire and capacity to eat, while ratings of satiety increased. Interestingly, subjects actually reported that eating all their food within a 6-hour period was a greater challenge than enduring the 18-hour fast, highlighting the feasibility of these interventions in future settings inside and outside of the laboratory.

The role of your circadian clock

The study we’ve been examining wasn’t just about assessing the health benefits of reducing a person’s feeding window, but also when the feeding occurs — it incorporated both fasting and biological rhythms.

We each have many so-called circadian clocks that regulate metabolism in response to different nutrients and based on the timing of food intake. In a paper called, Circadian clocks and insulin resistance, Dr. Dirk Jan Stenvers and his collaborators investigated the effect such “clocks” have on our biology and health.

The circadian timing system consists of a central brain clock in a part of your brain called the hypothalamic suprachiasmatic nucleus, as well as in various peripheral tissue clocks.

Suprachiasmatic Nucleus controls circadian rhythms

The circadian timing system is responsible for the coordination of many daily processes, including the daily rhythm in human glucose metabolism. The central clock regulates food intake, energy expenditure and whole-body insulin sensitivity, which are fine-tuned by local peripheral clocks.

For instance, the peripheral clock in the gut regulates glucose absorption, peripheral clocks in muscle, adipose tissue and liver regulate local insulin sensitivity, and the peripheral clock in the pancreas regulates insulin secretion.

Misalignment between different components of the circadian timing system and daily rhythms of sleep–wake behavior or food intake as a result of genetic, environmental or behavioral factors might be an important contributor to the development of insulin resistance. Specifically, clock gene mutations, exposure to artificial light–dark cycles, disturbed sleep, shift work and social jet lag are factors that might contribute to circadian disruption.

The point of all of this clock business is that food timing matters. As the Professor of Regulatory Biology Laboratory at the Salk Institute, Dr. Satchin Panda puts it:

When you eat is more important than what you eat.” (More here.)

Key endocrine functions such as insulin secretion and insulin sensitivity appear to be optimal in the morning, suggesting that concentrating food intake within the earlier daylight hours is superior for circadian alignment.

Which is what a scientist named Nimet Maherali, PhD found out.


Reverse Prediabetes by Eating Earlier, says Dr. Maherali

In her first-hand account, Dr. Nimet Maherali — who has studied diabetes at Harvard University and is developing a therapy for type 2 diabetes. — describes how she had more to learn about controlling and even reversing this disease through a Time Restricted Eating (TRE) approach.

She had a great impetus — she found out that she’s prediabetic.

reverse prediabetes

Dr. Nimet Maherali

It happened to Dr. Maherali like it does to most of us whose harried, unexamined lifestyle leads to insulin insensitivity and prediabetic blood glucose numbers. She gradually became overweight and ate whenever she could as she strenuously applied himself to her profession.

Dr. Maherali TRE Protocol

Once she was diagnosed as prediabetic, Dr. Maherali became determined to improve her blood glucose numbers and insulin sensitivity. She remembered the name of a researcher, Satchin Panda, whose research showed that the timing of food intake has important consequences for metabolic health.

Two studies on this caught her attention:

  1. Mice given food during active/waking hours are metabolically healthier compared to mice given food during sleeping hours. (4)
  2. Mice exposed to food for 8 hours a day versus 24 hours a day are protected from obesity and metabolic disease, despite consuming the same number of calories. (5)

It wasn’t clear to her whether this protocol could be applied to reversing insulin resistance in humans, but the underlying mechanism made sense, and it seemed worth trying. She decided to limit his food intake to an 8-hour window each day, with no change in food type or quantity.

Dr. Maherali didn’t specify when her feeding window began each day, but said it ended at 8:00 PM; the math then suggests she began eating at noon. In three days her fasting blood glucose levels to return to normal, but her average glucose test — the HbA1c — remained at the prediabetic level of 6.1%

Nervous, she contacted Dr. Satchin, who suggested to two things:

  1. Further cut the feeding window from eight hours (12:00 PM to 8:00 PM) to six or seven hours, and
  2. Eat oats and lentils to help with the longer fasting times, given that they’re both satiating.

Dr. Maherali did change her TRE plan, but not by reducing the feeding window to under eight hours. What she did is to do all his eating earlier in the day, between 10:30 AM and 6:30 PM. In addition, she restricted all refined carbohydrates – no added sugar, no bread, no potatoes, no pasta, no rice, no processed fruit juice.

Her TRE Challenges

Dr. Maherali faced two challenges on his TRE program:

  1. Eating enough food during the given time window. She addressed this being mindful that she not become so distracted by work and the events of his life that he didn’t eat enough during her feeding window.
  2. Being ravenous during the second week on TRE. She dealt with this by drinking water and after six weeks, became accustomed to the protocol.
Her Health Improvements from TRE

After two months on TRE with no refined carbohydrates:

  • Weight loss of 13 pounds, and
  • A loss of two inches around the lower waist (belly) – an area that was before intractable to his weight loss efforts.

After six months on TRE:

  • HbA1c was one percentage point lower – from 6.1% to 5.1% – she’s longer pre-diabetic.

After eight months on TRE:

  • From the two month mark on, she became less restrictive about food choices, including the reintroduction of some refined carbs, without gaining weight. and was able to enjoy a full range of holiday foods.
  • She lost 20 pounds, or 12% of his starting body weight.
  • She lost four inches around the waistline.
Dr. Maherali’s Overall TRE Assessment
  • It provides one clear rule he can follow — eat within a specific time window.
  • It worked for her friend who lost 28 pounds in four months, about 13% of body weight, using a fasting time of ~14 hours per night. This person did not overtly restrict food types (aside from eliminating 1-2 sodas per week), and did not feel deprived on this diet.
  • It improved her sleep quality, skin, and heart rate (lower pulse).
  • When we eat has profound implications for health, independent of food type or quantity, although quality macronutrients (protein, carbs, fats) will amplify better health outcomes.


Your Takeaway

You can improve many biomarkers for health, particularly your metabolic health, by doing just three things:

  • Reducing the time span within which you eat to less than 12 hours; and
  • Stop all eating and drinking (except water) by 7:00 PM or earlier, which will best align you with your circadian rhythms.
  • Give your self a relief valve; meaning, when you feel you need a break, return to your comfort zone rather than abandon the TRE protocol entirely.

TRE is simple, but hard to do.

If you want to reverse prediabetes, I strongly recommend that you give TRE a whirl, but approach it slowly. Try reducing your feeding window by only 1/2 hour each week, and pushing back the last hour you eat at night by 1/2 hour each week as well.

And know that there’s no way to get around feeling hungry at first. You’ll have to become accustomed to that feeling without panicking. Try drinking water. If that doesn’t help, add some cold pressed organic apple cider vinegar to the water or herbal tea. Eventually, exclude it so that you’re only drinking water.

One last word on the matter is to recruit a friend, or better yet, whomever you live and eat with. It’s very helpful to have someone to lean on when you seek to change something so ingrained as when you eat, because change is hard.



Last Updated on February 7, 2024 by Joe Garma

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Joe Garma

I help people live with more vitality and strength. I'm a big believer in sustainability, and am a bit nutty about optimizing my diet, supplements, hormones and exercise. To get exclusive Updates, tips and be on your way to a stronger, more youthful body, join my weekly Newsletter. You can also find me on LinkedIn, Twitter and Instagram.

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