How Carbs vs Fat Affect Hunger Hormone (Leptin): Weight Loss without Hunger?! | High Carb Science


PhD student in neuroscience shares results of a study on how fats versus carbs differentially affect your Leptin, which is a hormone responsible for burning fat and feeling full! Part of my series on the science behind high carb low fat diets.



  1. Fat doesnt satisfy my hunger , The reason u arent hungry on keto thanks to ur blood sugar but most evidences show that there is too little connection between glysemic index and hunger

  2. weird! I get it the other way around. I am not hungry on low carb if I keep my fat high enough. And I lift heavy weights 5 to 6 times a week. I get barely hungry. Sometimes not even hungry. And I am very lean as my picture shows. Maybe people react to fat and carbs differently.

  3. This is indeed a good overview of the effect of leptin upon hunger etc however, leptin is released from the fat cells and so higher carbs will increase fat stores and correspondingly increase leptin. Now the problem comes as a result of continued elevation of insulin through over consumption of carbs. This results Is a down regulation of the receptors in the hypothalamus resulting in leptin resistance. Leptin resistance is a major problem with the bodies fat regulation and can only be reversed by attempting to up regulate the receptors by decreasing carb consumption. This isn't an attempt to discredit what your saying and the research you site is accurate, indeed carbs have a more profound effect upon leptin and here lies the problem. We live in a world where insulin is constantly elevated through highly processed food. This results in the body totally getting out of balance and the bodies fuel gauge becomes broken. Once we stop responding to leptin we feel hungry even though we are laying down more fat and the more we eat the more fat we store and so the cycle continues. The way to reverse this is to reduce carb consumption in particular in people who already are metabolic resistant. Your advice isn't altogether untrue in that complex carbs in people who's metabolism isn't broken will help to slow insulin spikes and maintain an energy balance. However, as the research shows the leptin from fat is considerably less and indeed this isn't a bad thing in terms of preventing over stimulation at the hypothalamus and preventing leptin resistance. At least this is my understanding but I welcome debate and realise where diet is concerned there is never a linear solution and the science can become complex as a result of so many individual responses to macronutrients. A great post though and this isn't intended to be a criticism more of an extension and clarification of what you say. Regards x

  4. I've been on a LCHF diet for a few months now and I'm fairly clued up how it all works, but I only watched this youtube because you're so pretty. But obviously very smart too. Thanks.

  5. i'm not dieting or anything right now, but my teenage years i did an all fruit diet for a few years, and was always always hungry and lacked energy. why is that? do we need grains/ complex carbs for the leptin effect?

  6. Great topic and just to say up front I am a high raw vegan. It would be interesting to know what they used as "carbs" in the study. My body gets horrible inflammation (I have several autoimmune diseases) from cooked grains, as they damage my gastrointestinal tract. I always gained weight easily when I eat cooked grains, and of course I don't eat them raw sprouted either. But if I eat raw fruit carbs, I have no inflammation and don't gain weight. Some studies about "sugar" being supposedly bad for you use high fructose corn syrup in the studies, and then the researchers infer somehow from their negative conclusions about HFCS that all "sugar" is bad, including fruit. How does HFCS have any external validity to anything other than HFCS? In fact, the few studies that have used whole raw fruit instead of a high fructose sugar solution have had different results, finding that whole raw fruit actually has the opposite effect on insulin and even reduces diabetes, etc. My view is that the scientists conducting most nutritional studies are somehow not nuanced enough to see that applying chemical reactions (refining, solvents, fractionating, etc.) or heat (cooking) changes what something is and how it acts on the body versus the whole raw state. It's surprising because the average person has more common sense. "Protein" could be salmon, estrogenizing soybeans, pea protein isolate, nutritional yeast, or other things, so I fail to see how helpful it would be to study the effects of "protein," when the effect of soy protein isolate might be different from nutritional yeast for example. We  already know soy is an endocrine disruptor, but maybe the others aren't for just one example. So were the "carbs" in the study high fructose corn syrup? Brown rice syrup? Cooked sweet potato? Cooked potato (nightshades have particular concerns with solanine). Or raw fruits like bananas or mangoes. I do not disagree with the results of this study, but it would be helpful if researchers didn't just assume a macronutrient is a macronutrient is a macronutrient and that there is external validity from studying "carbs" or "protein" or "fat." With Hashimoto's, my body tolerates whole food avocados well, but give me refined oils and I get inflammation. From that alone I can tell you again that a fat is not a fat is not a fat either. This is why, as someone with statistical training myself, I take a lot of studies with a grain of salt until I have read exactly what they were trying to do, what they used, and their methodology. Some people claim that chocolate or coffee or green tea are good for you just because they contain antioxidants, but you have to look at the whole food that it is- they all contain methylxanthines which give some people like me tachycardia. And methylxanthines raise stroke risk, risk of birth defects, anxiety disorders and mental illness, risk of alzheimers, etc. So you can't look at one thing they contain like antioxidants as an excuse to label them healthy, but people do, so the multibillion dollar coffee and chocolate industries can sell more of them to people who now think they are healthy. If you are planning to be a researcher one day, I would hope that you will do a better job than what people have done in the past to distinguish these nuances between things when you are involved in study design.


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