My single best weight-loss tip

Weight scale with a measuring tape. Concept- lifestyle, sports and diet for weight loss. Copy space. On the measuring scale written word - HELP!

Just following up on our post from last week – Robert – I wanted to share with you my single best weight-loss tip.

In your body, nothing happens by accident. Every single physiologic process is a tight orchestration of hormonal signals. Whether our heart beats faster or slower is tightly controlled by hormones. Whether we urinate a lot or a little is tightly controlled by hormones. Whether the calories we eat are burned as energy or stored as body fat is also tightly controlled by hormones. So, the main problem of obesity is not necessarily the calories we eat, but how they are spent. And the main hormone we need to know about is insulin.

Insulin is a fat-storing hormone. There’s nothing wrong with that – that is simply its job. When we eat, insulin goes up, signaling the body to store some food energy as body fat. When we don’t eat, then insulin goes down, signaling the body to burn this stored energy (body fat). Higher than usual insulin levels tell our body to store more food energy as body fat.

Hormones are central to obesity as is everything about human metabolism, including body weight. A critical physiological variable such as body fatness is not left up to only the vagaries of daily caloric intake and exercise. If early humans were too fat, they could not easily run and catch prey and would be more easily caught themselves. If they were too skinny, they would not be able to survive the lean times. Body fatness is a critical determinant of species survival.


As such, we rely on hormones to precisely and tightly regulate body fat. We don’t consciously control our body weight any more than we control our heart rates or our body temperatures. These are automatically regulated, and so is our weight. Hormones tell us we are hungry (ghrelin). Hormones tell us we are full (peptide YY, cholecystokinin). Hormones increase energy expenditure (adrenalin). Hormones shut down energy expenditure (thyroid hormone). Obesity is a hormonal dysregulation of fat accumulation. We get fat because we’ve given our body the hormonal signal to gain body fat. And those hormonal signals go up or down according to our diet.

Obesity is a hormonal, not a caloric imbalance.

Insulin levels are almost 20 percent higher in obese subjects, and these elevated levels are strongly correlated to important indices such as waist circumference and waist/hip ratio. Does high insulin cause obesity?

The “insulin causes obesity” hypothesis is easily tested. If you give insulin to a random group of people, will they gain fat? The short answer is an emphatic “Yes!” Patients who use insulin regularly and physicians who prescribe it already know the awful truth: the more insulin you give, the more obesity you get. Numerous studies have already demonstrated this fact. Insulin causes weight gain.

In the landmark 1993 Diabetes Control and Complications Trial, researchers compared a standard dose of insulin to a high dose designed to tightly control blood sugars in type 1 diabetic patients. Large insulin doses controlled blood sugars better, but what happened to their weight? Participants in the high-dose group gained, on average, approximately 9.8 pounds (4.5 kilograms) more than participants in the standard group. More than 30 percent of patients experienced “major” weight gain!

Prior to the study, both groups were more or less equal in weight, with little obesity. The only difference between the groups was the amount of insulin administered. Insulin levels were increased. Patients gained weight. Insulin causes obesity. As insulin goes up, one effect is that the body set weight goes up. The hypothalamus sends out hormonal signals to the body to gain weight and we become hungry and eat. If we deliberately restrict caloric intake, then our total energy expenditure will decrease. The result may still be the same – weight gain.


Once we understand that obesity is a hormonal imbalance, we can begin to treat it. If we believe that excess calories alone cause obesity, then the treatment is to reduce calories. But this method has been a long-term failure. However, if too much insulin causes obesity, then it becomes clear that we need to lower insulin levels.

The question is not how to balance calories; the question is how to balance our hormones especially insulin. There are really only two ways that insulin increases. Either:

  1. We eat more foods that stimulate insulin
  2. We eat the same insulin-stimulating foods, but more frequently.

My book, The Obesity Code laid out the science behind weight gain and how to apply that knowledge to lose weight. It forms the theory behind the IDM program’s many successes over these many years. This book’s goal is to embrace these ideas and make it easier to implement in day to day life.


My key to long lasting weight control is to control the main hormone responsible, which is insulin. There are no drugs that can control insulin. Controlling insulin requires a change in our diet, which is composed of two factors – how high the insulin levels are after meals, and how long they persist. This boils down to two simple factors:

  1. What we eat – determines how high insulin spikes
  2. When we eat – determines how persistent insulin is

Most diets concern themselves with only the first question and therefore fail over the long term. It is not possible to address only half the problem and expect success.

In terms of the foods, this is not a low-calorie diet. This is not even necessarily a low-carbohydrate diet. This is not a vegetarian diet. This is not a low-fat diet. This is not a carnivore diet. This is a diet designed to lower insulin levels because insulin is the physiologic trigger of fat storage. If you want to lower fat storage, you need to lower insulin, and this may be done even with a high-carbohydrate diet.

Many traditional societies have eaten carbohydrate-based diets without suffering from rampant obesity. In the 1970s, before the obesity epidemic, the Irish were loving their potatoes. The Asians were loving their white rice. The French were loving their bread.

Even in America, let’s remember the 1970s. Disco was sweeping the nation. Star Wars and Jaws played to packed theatres. If you looked at an old photograph from that era, perhaps you might be amazed at several things. First, why anybody ever thought bell bottoms were cool. Second, it’s amazing just how little obesity there is. Take a look at some old high school yearbooks from the 1970s. There is virtually no obesity. Perhaps one child in a hundred.

What was the diet of the 1970s? They were eating white bread and jam. They were eating ice cream. They were eating Oreo cookies. There were not eating whole-wheat pasta. They were not eating quinoa. They were not eating kale. They were not counting calories. They were not counting net carbs. They were not even really exercising much. These people were doing everything ‘wrong’ yet, seemingly effortlessly, there was no obesity. Why?

What about the diet of the Chinese in the 1980s? They were eating tons of white rice. On average, over 300 grams per day, compared to a low carb diet of less than 50 grams and all highly refined. Yet they had virtually no obesity. Why?

What about the diet of the Okinawan? Over 80% carbohydrates, and mostly sweet potato, which has some sugar in it. What about the Irish in the 1970s, with their beloved beer and potatoes? They didn’t think twice about what they were eating, but until recently there was almost no obesity. Why?

The answer is simple. Come closer. Listen carefully.


They were not eating all the time.

When you don’t eat, this is technically known as ‘fasting’. This is the reason there is the English word ‘break fast’ or breakfast, the meal that breaks your fast. During your sleep, you are (presumably) not eating and therefore fasting. This allows time for your body to digest the foods, process the nutrients and burn the rest for energy to power your vital organs and muscles. In order to maintain a stable weight, you must balance feeding and fasting.

During feeding, you store food energy as body fat. During fasting, you burn body fat for energy. If you balance those two, your weight will remain stable. If you are predominantly feeding, you will gain weight. If you are predominantly fasting, you will lose weight. So, here’s my best single tip for weight loss. It’s so simple and obvious that even a 5-year old could have come up with it.

Don’t eat all the time.

Unfortunately, most nutritional authorities tell you the exact opposite. Eat six times a day. Eat lots of snacks. Eat before you go to bed. Eat, eat, eat – even to lose weight! It sounds backwards because it is backwards. Instead, it may be better to use intermittent fasting, a dietary technique used successfully for countless generations.

Also, check out the free Facebook support group – The Obesity Code Network for fasting support and education.

Dr. Jason Fung

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Dr. Fung’s top posts

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Top comments

  1. Joe
    Preach Dr Fung preach! Great article. Meal timing is of absolute importance. I start the day with a black coffee and just see what happens. Sometimes the first meal is at 1pm, sometimes 3pm. It just depends on how I feel. I try to listen to my body’s signals and even if hunger does develop, sometimes I like to push through it and lengthen my fast.

    This site is too obsessed with keto this and keto that! Stick to 20g of carbs or 50g of carbs! Who wants to eat in such a scientific way where every single thing is measured and weighed! Meal timing, intermittent fasting, longer fasts....these are the keys to healing the gut....I would say more so that just dedicating your life to a rigid diet.

    The truth is that human metabolism is so complex that we are probably not even scratching the surface when it comes to understanding how we digest different foods. But one thing we can agree on (as Dr Fungs article clearly states) is that we cannot eat all the time. The digestive system needs a break from food to help it digest food thoroughly , repair, heal, rejuvenate etc.

    Fasting is the cure! But in modern day society....with the junk food industry pushing its snacks, food availability, supermarkets on every street corner etc etc....fasting is seen to be some sort of weird dangerous practice!

    Read more →
  2. Jude
    Don't forget about the possible effects of endocrine disrupting chemicals accumulating since the 1970's as an additional explanation to frequency of food intake.
    Read more →
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All comments

  1. Elasa Roy
    Thanks for sharing the amazing benefits of the high-intensity interval for weight loss. It is more effective than moderate exercise for weight loss.
  2. Bharat
    Eat between 12 pm to 6 pm. Insulin is secretes low in the afternoon
  3. Bharat
    High insulin effects are resisted in the case of type 2 diabetes. So, we lose weight despite consuming high carbs and high insulin secretion. Weight loss from overweight to normal weight should not be seen as negative, especially when the body tries to get rid of the excess sugar in the blood through urine. Once we are on keto and intermittent fasting we again lose weight but if we add little bit carbs and sweets, we again gain weight. .
  4. 1 comment removed
  5. K. Balbierz
    Does anyone know if you can drink Kombucha when following the obesity code? If yes, should it only be on days you aren't fasting?
  6. Ace
    When he says that people in the 70s were fasting, what he’s talking about is that after dinner, around 7 pm, they were done. No midnight eating. They didn’t eat again until the next morning. And they didn’t eat in between their 3 meals. You need three hours of no eating in between meals to get insulin to drop. And that’s the main point. Large gaps where no food is ingested drops insulin. This prevents high blood sugar and obesity. But if you keep eating every hour or couple hours, insulin never has a chance to drop and your blood sugar remains high, thereby promoting obesity.
  7. 1 comment removed
  8. Jade
    I just want to know how to stop losing weight. Within 5 months, I was at my ideal weight. Though my weight loss has decreased I am still losing weight. I was underweight prior to having children and aging. I don't want to get back there, but it seems to be what is happening. I bought a Fitbit and count calories to ensure I am putting in as much as I am burning. However, the weight keeps falling off. I can't go back to what I was eating because it will make me violently sick. So, what is the next step?
    Reply: #59
  9. Kristin Parker Team Diet Doctor

    I just want to know how to stop losing weight. Within 5 months, I was at my ideal weight. Though my weight loss has decreased I am still losing weight. I was underweight prior to having children and aging. I don't want to get back there, but it seems to be what is happening. I bought a Fitbit and count calories to ensure I am putting in as much as I am burning. However, the weight keeps falling off. I can't go back to what I was eating because it will make me violently sick. So, what is the next step?

    You may find this guide helpful!

  10. 1 comment removed
  11. conchita
    All I want to know is how to lower my body set weight. It has increased from 102 lbs to 115 lbs in 23 years and I just want it to go back to 102. My BSW was 108 for around 15 years and is @115 today although my clothes fit the same as those 20+ years ago. Please advise. I am 5'0" tall and weighed 97 lbs in college with zero diets or trying. It was just the way it was.
    Reply: #62
  12. Craig
    Don't eat until 11 a.m. and stop by 7 p.m. and make that pretty much a lifestyle.
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