How and Why Intermittent Fasting Works for Weight Loss
With 16 hours, intermittent fasting forces your body to use up all your glucose stores, after which you burn stored fat. If you do a workout at the end of your fast you will burn even more fat.
The added benefit for diabetes is that after 8 hours your body does not have glucose, and therefore has no need to produce insulin. On a daily basis your glucose level will significantly drop, and reset itself.
How you Gain Weight over Time
The corollary to intermittent fasting is the traditional meal schedule. You have dinner at 6:00pm. Your glucose will last you until 2:00pm. You then have a snack at 10:00pm, just before going to bed. Your glucose stores will last until at least 8:00am, but then you have breakfast at 8:00am, forcing your body to create more glucose, which will last you until 4:00pm. Lunch is at 12:00, when you again make glucose, which will last you until 8:00pm. Dinner is again at 6:00pm. With around the clock snacking and meals your body never uses up all its glucose. In fact, you produce an excess of glucose, which is then stored as body fat. As well, there is no way to use up stored body fat as a fuel source, so you cannot lose weight.
Over time on a daily basis at the end of the day you have a small excess of glucose, which is stored as body fat. As the years go by this accumulates and you gain weight. Body fat is impossible to remove, because you never need to use it as an energy source. With the modern diet you always have access to sufficient food and therefore glucose.
Intermittent Fast and Diabetes
The general idea of intermittent fasting is that you regularly do not eat from the night before until noon the next day. This intermittent fast exhausts your existing blood sugar or glucose level and you produce much lower insulin amounts. Without excess insulin levels your insulin resistance goes way down, and thus reduces your diabetes risk. The body then switches and uses stored fat. You may also lose weight. There are also theories about your body getting its insulin level stuck, and an intermittent fast will reset this.
Fung, a nephrologist who authored the books The Obesity Code and The Complete Guide to Fasting, is one of the most vocal advocates of intermittent fasting, having seen its effects in his type 2 diabetes patients…
It was this observation that led him to intermittent fasting, as a way to quickly lower insulin in the body. Prolonged periods of low insulin force the body to turn to stored sugar as a fuel source, and when that’s been depleted, to turn to fat.
Insulin, a hormone made in the pancreas, helps the body use sugar for energy, but insulin resistance and prediabetes can occur when the body doesn’t use normal amounts of insulin properly. Diabetes is a leading cause of kidney failure.
Knowing what he does about insulin’s effect on weight gain, he says exercise is a very inefficient way to slim down. “There are a lot of health benefits, but they’re two totally separate issues,” he says. “If I had to guess, diet is 95% of the battle, and exercise is 5% of the battle. The problem is we over-emphasize exercise.
When Fung talks about your body using your fat for fuel, he’s talking about ketosis. To get into ketosis, you don’t give your body any of its preferred grab‘n go fuel—glucose—and force it to look for alternatives… the body will start shaking down fat cells for energy…
…“One way the body releases ketone bodies is through exhalation therefore making the breath sweet and fruity,” says New York-based dietician Amy Shapiro… Research has shown that breath acetone is reliable indication that you have gone into fat burning mode…
2018 Oct 23 Many intermittent fasters skip breakfast. Here’s why that’s not a good idea.
2017 Jan 31 Why You Should Start Skipping Breakfast
2018 Dec 16 The benefits of fasting: from the 5:2 diet to tricking the brain with low-calorie foods
2018 Dec 20 Is Intermittent Fasting Really Worth It?
2019 Jan 14 Fasting diets are going mainstream — ahead of the science. Here’s why.
Fasting may even help you stave off disease and live longer. Maybe. Just know that there are lots of question marks about the long-term health consequences of fasting. And, as Longo said, there’s a reason fasting has been around for so long but very few people do it regularly: “It’s too difficult.”
2019 Mar 09 How meal timings affect your waistline
2016 May 10 I’m an obesity doctor. I’ve seen long-term weight loss work. Here’s how.
Looking to their success stories, published both online and as highlighted by Anne Fletcher in her book exploring the registrants, Thin for Life, the one common theme is that while maintaining their losses requires ongoing effort, that effort isn’t perceived by these weight loss masters as a hardship but rather as just living with new lifestyles, and lifestyles that they enjoy.
This is something I’ve witnessed regularly in my own practice. Looking to my experiences working with thousands of patients over the course of the past dozen years, it’s clear that liking the life you’re living while you’re losing weight is the key to keeping it off…
The truth is there will come a point where you can’t happily live any better — where you can’t happily eat less and you can’t happily exercise more — and your weight, living with that life, is your best weight. In every other area of our lives we readily accept our best efforts as great, and we need to do that with weight and healthful living too.
2019 June 04 Intermittent Fasting Made My Life Easier, and Happier
2018 May 28 7 Natural Ways to Raise Testosterone Levels (Raise Your T for FREE) This guy mentions that intermittent fasting raises testosterone and human growth hormone, naturally. reduce zeno-estrogen levels: don’t eat or drink out of heated up plastic
2019 June 18 How to Get Faster Results with Intermittent Fasting: He mentions sarcopenia and weight lifting in his IF talk
Jim Stoppani On Intermittent Fasting for Muscle Gains: intermittent fasting and HIIT. HIIT burns carbs during the workout, but burns fat after workout
What is intermittent fasting?, How to Maximize Fat Burning, Dr. Jason Feng, Dr. Jason Fung – ‘Therapeutic Fasting – Solving the Two-Compartment Problem’

kevin hall study on dieting, oxidation rate vs days of fasting, seen from Jason Feng
There IS no secret…it’s Intermittent Fasting: An interesting piece of info is to do your workout at the end of your intermittent fast in order to maximize your fat burning. You make your first meal of the day your post-workout meal. This makes sense.
Eat, Fast and Live Longer:by Michael Mosley
I Don’t Get Hungry with Intermittent Fasting
I don’t get hungry, even after a 17 hr fast, and I don’t know why. Here’s a possible answer:
Hunger is mostly run by the hormone “ghrelin”. Studies show that a high carbohydrate diet causes a higher level of ghrelin, AKA more hunger. That same study found that higher levels of fat in the diet significantly decreases the hunger hormone. Lesson learned here: when your body uses fat for more of your energy vs. carbs, your cravings go down…
Intermittent fasting taps into your fat burning mechanisms and provides energy for your body by pulling from your stored fat energy systems. This results in boosted energy levels as well as natural fat loss. Because your body has energy flowing from your fat burning mechanisms, it doesn’t trigger ghrelin to go up…
Another theory is that by fasting your glucose level is reset to zero, your body produces human growth hormone and you turn to the alternative fuel source, fat. With HGH and a fuel source there is no need for your body to “ask for more food” by making you hungry.
When you sleep, your body produces anti-hunger substances like HGH (human growth hormone). Your insulin falls to base overnight. These things and others suppress hunger. When you wake and stay fasted, NONE of those things change just because you have woken up. Yes, if your body is used to eating right after waking you will get hungry but if you have been doing IF, you will just stay non-hungry.
Studies have shown that if you don’t eat after waking, not only will your insulin stay at base and your HGH not fall, your HGH will actually slowly RISE until you decide to eat. This high level of HGH has the primary effect of sparing (and even building) muscle during your fasts – by sparing your muscle it forces your body to use FAT for fuel which is what you want. But the nice secondary effect of keeping your HGH high while fasting is that is keeps your appetite suppressed! HGH stays elevated until insulin spikes, i.e. until you decide to eat.
It looks like intermittent fasting and not feeling hungry is a pretty common positive side effect.
Time-Restricted Eating by Ted Naiman MD This guide offers a very clear explanation of intermittent fasting and its benefits. He talks about the Leangains method, which is the 16-8 intermittent fast.

Fat burning during fasting, sugar/fat burning by time. by Ted Naiman, MD. After 12 hours your body changes from burning sugar to burning fat.
This chart is interesting because it shows that after 12 hours your glucose is depleted and your body will then burn fat. If you do the 16-8 method you will burn fat for 4 hrs/day. Seven days a week of the 16-8 method results in an additional 28 hrs of fat burning. Exercise after 12 hours, during the glucose burning state will accelerate your fat burn.
Japanese Fasting Study Reveals Complex Metabolic Changes in the Human Body
Of all the tips he shares – eating right, cardio, gym, yoga, running and hiking in the mountains, surfing, swimming – the one that stands out is his intermittent fasting. “I take 18 hours off eating, six days out of seven. I won’t eat anything after 8pm or 9pm and then I won’t eat anything until 2pm the next day.
“It’s a little hard at first but once you get used to it, it’s been really rewarding. I’ve read a lot about the benefits of fasting for longevity, for your brain … and to maintain abs.”
When You Eat Breakfast and Dinner Could Affect Your Levels of Body Fat
Fifty seven percent of individuals admitted that they didn’t think they could continue these meal time changes past the end of ten weeks. They also rated the diet a seven out of ten on a scale of difficulty. Seeing as the authors described this group of volunteers as “well-motivated” to follow the diet, these results might not bode well for the rest of us.
“As we have seen with these participants, fasting diets are difficult to follow and may not always be compatible with family and social life,” Johnston said “We therefore need to make sure they are flexible and conducive to real life, as the potential benefits of such diets are clear to see.”
Japanese Fasting Study Reveals Complex Metabolic Changes in the Human Body
…it’s safe to say that fasting is nowhere near as simple as it seems, and scientists are only beginning to bring the full picture into focus.
Why Backers of Intermittent Fasting Believe It Can Slow Aging: No proof of longer life
2020 Oct 12 Intermittent Fasting: Fad or Future? with Steven Gundry M.D., Jason Fung M.D., Carrie Diulus M.D.
2020 Dec 07 Intermittent Fasting vs Cutting Calories
My Fasting Notes after losing 100 pounds! Yikes! But there’s more…
How I FINALLY Stopped Gaining Weight – 3 Easy Steps: Less work, do cardio you enjoy, intermittent fasting (starts at 4:38)
Do this and 50% of your health problems will go away – Sadhguru about fasting: For bodily repair you need to have an empty stomach
A Doctor’s Guide to AUTOPHAGY and FASTING: Lose weight, reduce inflammation, and live longer!: There’s info about atophagy vs mTOR, and fasting and the female hormone cycle
Should WOMEN Try Intermittent Fasting?
Is calorie restriction and exercise overrated?! Fasting, 120 pounds lost, 2 years steady.; A weight loss journey, from 300+ down to 170, and how to keep it off using fasting.
What We Think We Know About Metabolism May Be Wrong
Central to their findings was that metabolism differs for all people across four distinct stages of life.
- There’s infancy, up until age 1, when calorie burning is at its peak, accelerating until it is 50 percent above the adult rate.
- Then, from age 1 to about age 20, metabolism gradually slows by about 3 percent a year.
- From age 20 to 60, it holds steady.
- And, after age 60, it declines by about 0.7 percent a year.
Metabolism TANKS As We Age | Here’s How To Stop It: Theory is to reduce the tax on your metabolism by eating clean, exercise, low stress, good quality sleep. Your metabolism will therefore have sufficient energy to repair your body, this slowing aging.
Eat early, and less often
Clinical data shows that intermittent fasting — an eating pattern where you cycle between periods of eating and fasting — can improve insulin stability, cholesterol levels, blood pressure, mental alertness and energy.
What Is Intermittent Fasting and Does It Really Work?: The best diet is the one where you are healthy, hydrated and living your best life.
A Potential Downside of Intermittent Fasting: A rigorous three-month study found that people lost little weight, and much of that may have been from muscle.
“The pancreas produces insulin, a hormone that helps the body process glucose in the blood and store it as readily available energy in our liver and muscle cells,” Patel explains. “When these same cells are packed with fat, the glucose has nowhere to go but to continue circulating through the bloodstream.” That is because excess fat stops the insulin receptor from working. Type 2 diabetes occurs when blood glucose levels are consistently elevated and outside the normal range.
“Our liver and muscle cells are not designed to store fat; they are designed to store glucose. So, when there’s a build-up of fat in these cells, the insulin cannot do its job of processing and storing glucose. The pancreas will produce extra insulin to compensate initially, but this can only go on for so long.
“At the same time, the liver cells are unable to use insulin effectively, so that’s a double whammy for blood glucose levels.”
An interesting analysis of the liver, glucose processing and Type 2 diabetes, but I disagree with how to reverse it. This article spreads many traditional views that have long been debunked, such as a low-fat diet and the need for breakfast. Body processes are much more complex than they appear.
Weight Loss (Hormones vs Calorie Counting): Dr. Jason Fung
Terry Crews on intermittent fasting: I don’t really know who he is, but he is enthusiastic!
How To Easily LOSE FAT Even Around The Holidays: Ryan Hummiston is a hard core strength training coach.
2017 Dec 20: How Intermittent Fasting Affects Your Body and Brain | The Human Body: pretty good summary vid on some of the benefits of Intermittent Fasting
Although he frequently faces temptation and finds it difficult to refuse carbs at family and friends’ homes because social norms require people to be polite, Farooq knows how to whizz back into ketosis: by fasting.
“I often eat only one meal a day [OMAD – often combined with the keto diet] or I fast for at least 16 hours a day, and I can say that today I am the healthiest I have ever been in my entire life,” he says.
2022 Feb 04 Thomas Delauer Changes My Mind? Intermittent Fasting: Intermittent fasting tips
2022 Feb 21 Top 5 Intermittent Fasting Advantages | Jason Fung
2022 May New Study on Time-Restricted Eating and Weight Loss
2023 Apr 24 Intermittent Fasting for Fatty Liver | New clinical trial
2023 May 27 5 Newest Advancements in Fasting Science that Have Changed My Mind: I’m unsure if I believe these studies, but they do sound promising.
2020 Jul 13 How to lower A1C ¦ How I reduced my A1C from 10% to below 5%: IF at 9:58
2021 Jan 11 Is Intermittent Fasting Good for Type 2 Diabetes?
2023 Jul 31 Intermittent Fasting: Why You Should Do It Talking With Docs
2023 April Everything You Thought You Knew About Protein Is Wrong | Stanford’s Professor Christopher Gardner: The average North American does not need to worry about protein intake, We have enough with just what we eat, 31:19 mentions sarcopenia. If you just ate the minimum amount of food, plant based diets might be deficient in some of the 7 of 20 amino acids that we cannot produce. But we don’t eat the minimum. Rather we eat twice the minimum or more, so we always receive the necessary 7 amino acids required. This is the best summary of proteins I have every heard.
2023 Apr How to reverse blood pressure naturally? | Dr Pal: Eat too much sugar, leading to insulin resistance, leading to fat storage, leading to blocked arteries and veins, leading to high blood pressure, therefore reduce foods that increase blood sugar. The best way to do this is 1) fasting (min 12 hrs, to 16hrs) reduce carbs, second helpings 3) don’t eat processed foods, which has added sugars. “Remember, one belly at a time, it is ABSolutely important”
2023 Oct 27 When does autophagy begin after initiation of a fast?: nadir mir ali
2023 Nov 03 Fasting can reverse type2 diabetesDr. Jason Fung
references:
–Effect of an Intermittent Calorie-restricted Diet on Type 2 Diabetes Remission: A Randomized Controlled Trial
Efficacy and Safety of Intermittent Fasting in People With Insulin-Treated Type 2 Diabetes (INTERFAST-2)-A Randomized Controlled Trial
–Intermittent fasting plus early time-restricted eating versus calorie restriction and standard care in adults at risk of type 2 diabetes: a randomized controlled trial
2021 Nov 11 Intermittent fasting is a proven way of losing weight quickly – but it may not work for everyone
2018 may 14 Intermittent fasting is more than just a weight-loss regimen, says 10-year veteran
2023 Dec 01 Clean Intermittent Fasting & OMAD: “the nOMADer what club”, haha!
2023 Dec 07 Is Insulin Resistance Keeping You From Gaining Muscle? 13:06 “If you lose a bunch of fat, that is the number one way to become more insulin sensitive, is to get leaner. it is the most predictable thing I’ve ever seen in blood work, it’s just a..miracle”
2023 Jul Take Creatine for Fat Loss: Dr. Darren Candow; creatine makes muscles bigger, resulting in burning more glucose, indirectly leading to fat loss
2021 Does Intermittent Fasting, WITHOUT WEIGHT LOSS, improve your Health? [Study Breakdown]: Physionic, a very interesting analysis of a study about 80-6 intermittent fasting, its effects, all without weight loss. There seem to be benefits beyond weight loss.
2021 The Intermittent FASTING MISTAKES That Make You GAIN WEIGHT!: Dave Asprey, taking intermittent fasting up another level to a spiritual level
2022 The BIGGEST MISTAKES People Make When Trying To LOSE WEIGHT!: Dr. Jason Fung, 14:49 fasting
2024 Jan 15 The best way to do intermittent fasting: Gin Stephens and Prof. Tim Spector, 03:06 talks about the microbiome’s circadian rhythm, based on giving them time to eat through your fast
2023 June Intermittent Fasting For Weight Loss | MD Advice To Help You Lose Weight: Kim Foster, M.D., 3:25 mentions Dr Jason Fung
2024 Jan 23 The SIMPLE Way To Make Your Body KILL BELLY FAT! Dr Jason Fung
2024 Feb 17 The 36-hour monk fast British PM Rishi Sunak practises: a dietitian reveals how it works, and followers praise its physical and mental rewards: A good article, and very accurate. Missed: Ketosis can be extended with a low carb/keto diet
2023 Nov 20 How intermittent fasting may protect brain health and help extend longevity – expert tips on how to begin and how long to fast for: talks about insulin resistance and its effects on the brain
2024 Jan 16 The Truth about Fasting: How It Works: Dr. Eric Berg, a really clear explanation of how fasting works and what it can accomplish. I’m still not sure about the prolonged (>24 hr) fasting
2019 Dec 19 Ep:17 Ketogenic Rules for: Intermittent Fasting pt 1: From our hunter gatherer background, our bodies are adapted to long bouts of not eating, but still surviving. We have progressed to a point where eating is more an emotional event rather than a biological necessity. People from South Asia and East Asia, where carbs are the norm, have adopted the Western lifestyle and have then developed diabetes. Intermittent fasting is a method to get us back to what we need to biologically survive and to counteract the new social rules that are making us unhealthy. We are living in a carbohydrate addicted world.
2024 Dec 05 Scientists Just Found Your Brain’s Hidden Defence System: Dr Dan Maggs, on how ketones can help repair the brain and possibly reduce Alzheimer’s, intermittent fasting and ketogenic diets creates more ketones
2024 Dec 12 Dr. Jason Fung Dec 12, 2024 Livestream13:30 Fr Fung mentions his intermittent fasting and low carb program, addictive foods, ultra-processed foods, late night eating, keto diet, berberine, OMAD to reverse insulin resistance