This will hopefully be the first part of a mini series of articles looking at various hormones that impact our health and physique goals, addressing their basic function in a very simplified way and discussing strategies to (naturally) manipulate them in our favour. I should stress the 'simplified' part of the preceding sentence; hormones work together in hugely complex ways that are still being studied, no single hormone operates in a vacuum, but we can still learn a lot looking at them individually. Sounds exciting doesn't it? Yes, it does. Now we begin with the most important hormone that you probably haven't heard of: Leptin.
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| Don't underestimate this curly little fella |
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| I was going to put a fat person here, instead I put good looking people. You're welcome. |
The main roles of leptin are the regulation of appetite, fat mass and energy expenditure. When leptin is sufficiently high, your appetite is in line with your ideal calorie intake and your metabolism hums along nicely. If leptin levels drop, things get a lot less fun as your appetite will shoot through the roof, cravings hit hard and and your body hits the brakes on your metabolism. Researchers have performed experiments on rats where they cause a mutation to the leptin producing gene so no leptin is secreted. The result was rats that never stopped eating and turned into hilarious little blobs, furthermore, their immune systems were depressed and their cholesterol, triglyceride and insulin levels were off the the charts (that's bad). So now you have probably realised that having low leptin is tantamount to having AIDS, possibly worse; the good news is that this terrible affliction is reversible. That's low leptin, not AIDS; I'm not a miracle worker.
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| Obese furry animals, unlike obese humans, are actually quite cute. |
If you have been eating at (or slightly above) your hypothetical total daily energy expenditure (TDEE) number of calories for an extended period of time, the good news is that your leptin levels are likely fine. However, when undergoing caloric restriction you will find that you create a deficit, fat loss occurs quickly at first, but then leptin levels fall, fat loss gradually slows and then grinds to a halt. This, along with an increase in appetite spells doom for your diet. This makes perfect sense as an evolutionary survival mechanism; when there was no guarantee of food, a prolonged drop in caloric intake could mean the start of a famine so it would not be desirable for the human body to burn through all it's energy stores at a rapid pace. Rather they are conserved (so metabolism and thus fat oxidation rate drops) and signals are sent for the body to gather energy (so cravings for calorific foods hit). The problem these days is that us western world lot have it easy, we are generally too fat and looking at lean out and calorific food is everywhere; when we try to diet and leptin falls, the metabolism slowing is undesirable and the cravings are all-too-easy to succumb to.
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| Low leptin usually ends in a face full of delicious calorific crap |
Through these mechanisms leptin maintains a steady fat mass in humans; the existence of a bodyfat 'set-point' (a body fat percentage which each individual gravitates towards, which generally requires a fair amount of effort to move from) has long been observed in the fitness community. This is because when your fat levels drop below your set point your metabolism falls and hunger increases, so without a strong diet strategy and/or a dose of man-the-fuck-up your body fat creeps back up. Conversely when you decide that abs are for gays, the 'power look' is cool and that Nutella and banana sandwiches are better than female attention (yes, that was my summer), your body fat levels increase along with leptin. This means your metabolism takes a step up and your appetite is blunted, bringing your weight back down (to 92 kg for-fucking-ever).
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| The food of Gods |
If you are thinking that the answer to getting lean is a case of getting your leptin as high as possible, think again. Remember that leptin levels correlate with body fat, so obese people have sky high leptin levels; generally whatever is going on with obese people, we want to avoid. If you are constantly eating a large surplus, you will end up with similarly sky high leptin levels which can lead to your feedback system getting all sorts of messed up, with the currently believed mechanism being one of leptin resistance. This means your leptin receptors get desensitized, so the leptin that is secreted doesn't effectively deliver the message that you are 'fuelled' meaning you can be stuffing your face, but as your feedback system is broken, your body essentially 'lets' you keep eating and doesn't increase metabolism or blunt appetite sufficiently (as would occur in an individual with a fully functioning leptin receptors).
So, as is almost always the case with hormones, balance is what we are after. Fortunately for you fantastic readers, scientists and fitness experts have a pretty good idea of how best to achieve this balance:
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| A fine example of someone not being fat. |
- Don't be fat.
This is generally good advice for life but specifically in the scope of leptin, being fat means very high leptin levels, which likely means leptin resistance and a screwed up feedback system, keeping you fat. Leptin resistance will decrease with loss of body fat and exercise, so these should be a priority (as they should be anyway if you are fat). - Perform high intensity training
Heavy weights are the preference here, but high intensity cardio such as sprints, circuits, short-distance swimming, combat sport training etc. all also work. The key is intensity, this leads to a release of growth hormone, which has been shown to regulate leptin levels (as well as have a whole host of other positive effects which will be addressed in a future article). - Get sufficient sleep
At least 6 hours, preferable 8. Sleep is important for the optimal function of pretty much every hormone. Studies show that a lack of sleep leads to leptin falling below optimal levels, stimulating appetite and reducing metabolic rate.
- Don't regularly eat fuck tonnes of simple carbs
Smashing your fat face full of carby goodies is fun. I have experienced this. However, this leads to a big spike in blood sugar, which leads to a big spike in insulin, which leads to a rise in leptin. Do this regularly enough and you start becoming leptin resistant, not to mention insulin resistant, which is the fast road to type II diabetes. Not good. - When dieting to reduce body fat, implement re-feeds
Leptin levels dropping are an unavoidable side effect of dieting, what we need to do is limit the extent of this drop as much as possible. This is best achieved with periodic re-feeds; these are planned increases in calories (coming predominately from glucosidic carbs) which serves to bump leptin levels up significantly. How often and how large in magnitude these should be depends on a variety of factors including how lean you currently are, how large your caloric deficit and how long said deficit has been running. The leaner you are, the bigger your deficit and the longer you have been running a deficit, the more often and calorific your re-feeds should be. Blanket prescriptions, as usual, are very handwavey. You can choose to refeed at set intervals, for example doubling your carb intake on one day per 7-10 days; alternatively you can track your weight loss, appetite and general feelings then refeed more intensely when you see weight loss stalling, appetite increasing and lethargy setting in.
You may be thinking that refeeds present a sort of '3 steps forward, 1 step back' approach; in a way they do, in a way they don't. It is true that the refeeds days in and of themselves are not causing fat loss, however without them, calories would have to be cut more and more to see fat loss results, leaving you absolutely starved with a metabolism in the toilet. This is why crash dieting can lead to big weight gain after people lose a lot of weight through crash dieting. Their leptin levels are bottomed out, as is their metabolism and they are craving every delicious food under the sun. They then let themselves free on these foods and end up gaining all the weight back, regular with more. If you have got yourself into a mess like this, the answer is reverse dieting. You need to slowly add calories back in week by week to bring your leptin levels and metabolic rate back up without inducing a large amount of rebound fat gain.
As all this has been a bit approximate, I'll give an example of a few hypothetical situations:
A 6' 2.5'' 92kg, fairly lean, moderately attractive, large nosed gentleman wishes to lose fat. His TDEE is almost bang on 3000 calories, so he (smartly) decides on a 15% calorie deficit and eats 2550 calories a day. Hypothetically, 30% of these calories come from carbs, so he is eating 190g of carbs a day. He can either plan to have a day where he eats 380g carbs once every 7-10 days to keep his leptin levels high, or when he feels that fat loss is stalling and appetite is ramping up, he can have a couple of days where he eats 380g carbs, then go right back to eating at a deficit. If this hypothetical male wasn't such a geek who liked reading about human physiology, he might be clueless as to the workings of the leptin system, so when his fat loss stalls he cuts calories, then fat loss stalls again so he cuts calories again and so on. Before he knows it he is eating 1800 calories a day with no fat loss to show for it and feel like shit. To get out of this mess, he should slowly add calories back into his diet, for example eating 1850 calories a day for the next 3-5 days, then 1900 for a few days after that and so on until he is back up around his calculated TDEE for his weight and fat percentage. When he reaches this ideal amount of calories, he should eat at this level for at least 2-3 weeks to fully allow his metabolism to 'recover', then in future he shouldn't diet like such a retard and should read some science first.
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| Take heed, hypothetical male. |
So that's leptin. It's your friend, until it's your enemy. Like most things hormonal, it's a matter of balance, too low is bad, too high is also bad. Keep it in that happy middle ground; love your leptin and your leptin will love you, or at the very least it won't fuck you over.
