– You look like you’ve lost some weight.
– Yes, I have! I’ve lost 12 kg in 4 months. You remember, a year ago, I told you I would do my own diet, and I did!
– That’s great, congratulations!
– You know what I did? I stopped eating junk. I didn’t do anything else. I stopped eating chocolate bars and candy; cakes, cookies and ice cream; chips and fried foods, and that’s it. I eat everything: anything that is a whole food, and I do have bread and potatoes, rice and pasta, as well as cheese and fruit. I didn’t do anything crazy or radical, I just eliminated junk food from my diet.
– That’s really good. I’m happy for you. Keep it up!

This is how went a short conversation I had recently with a colleague who, a couple of years ago, was one of the 25 people who attended the talk I gave at ESAC: Water, sugar, protein and fat. It could be (I’d like to imagine) that the talk was like a little seed in her mind that was what eventually grew into enough of a motivation to start what she had been doing for a few months already, making her feel really great about it, as anyone would, of course. And I’m really happy for her, and also very happy to possibly having been a little positive influence somewhere along the line.

Another colleague stopped by my office in the spring to ask about the fitness club (a club to encourage people to exercise by subsidising part of the monthly membership to a great sports club close to where we work for which I was president for several years until a month ago or so). He mentioned in passing that he wanted to start doing sports in order to lose weight. Naturally, I immediately said that exercising wasn’t really the key to fat-loss. He was surprised, as most people are when they hear this. Being interested and inquisitive about this point (he works as a scientist, after all), I gave him a 10-minute summary of the biochemistry of fat loss, and he left very motivated to start on his fat-loss programme.

About one month later we crossed paths on the main road in front of the canteen. He looked much thinner: he actually looked quite trim considering that as little as four weeks before he not only looked but was definitely quite chubby.

– Things are going well, I see! You look like you’ve lost a lot of weight already.
– Yes, I’ve lost 10 kg. Now, after the first four weeks, I’ve started to eat carbs again, but I’m eating 1500 calories and exercising every day. I started eating some complex carbs because I need energy.

I masked my internal cringing, and just said “well, you are much leaner than you were. Good job and keep it up!” But I thought: What in the world!?! How did he come to think like this after I explained to him how fat loss works, and which he seemed to understand? The thing is, he did cut out all carbs for four weeks—there’s no way in the world he would have lost this much fat any other way—but for whatever reason, he now thought he should start again because he was exercising every day and therefore “needed energy”. He really didn’t understand the most important points I had tried to relate in that chat we had in my office. I am, in any case, very happy for him as well, because it is always better to be leaner than fatter, especially considering that a lot of the excess fat accumulating in our abdominal cavity is stuffed in between and all around our vital and digestive organs, putting constant pressure on everything in there, and that’s really bad.

Now, I would like to think that all of you readers of this blog already know what I want to point out and explain in regards to these two short fat-loss tales. Whether you do or not, I thought it was a good occasion to review the essentials of fat-loss in a quick and focused but more informal style than in other articles I have written. You are more than welcome to take a few minutes and try to guess what I’m about to explain about these two cases before moving your eye gaze down onto the first line of the next paragraph.

Why did the first colleague I talked about lose so much weight? Is it because she started exercising? No. She never exercised and still doesn’t. Is it because she starved herself on a low-calorie diet Weight Watchers style? No. She hasn’t been hungry because she hasn’t tried to eat a lot less, and has three meals a day without paying close attention to how much and is certainly not counting calories. Is it even because she stopped eating “junk food”? No, it’s not. The reason why she has lost this weight seemingly so easily is only because she markedly decreased the amount of sugar she ate, which immediately translated in lower blood sugar levels throughout the day and night, which in turn translated into lower insulin levels also throughout the day and night. As insulin drops, fat-burning starts.

Will she continue to lose her fat reserves indefinitely at this rate until there are none left? No, she won’t: fat utilisation, and therefore fat-loss rate, is inversely proportional to insulin levels. So, the lower the blood sugar, the lower the insulin, and the lower the insulin, the faster the fat-loss rate. Because she still eats sugar in the form of starches, the sugar/insulin concentration will only sometimes drop low enough for fat-burning to start, and will not drop very low and stay there to allow the metabolism to fully adapt and settle into a stable and more or less constant fat-burning mode. She will remain in intermittent fat-burning and sugar-burning. Because her fat reserves are at this stage still very large (from the organism’s perspective they are still effectively infinite), the relatively lower blood sugar for periods of several hours will prompt the body to continue to let go of these excessive fat reserves relatively easily until a steady state is reached and fat-loss stops. At that point she will still have plenty of excess body fat, but will be unable to lose any more without dropping insulin levels lower.

Of course, eliminating junk food—mostly commercial sweets and fried stuff—and feeding ourselves with actual food, no matter what it is, makes a huge difference. This is definitely the very first step in any change of diet towards better health. That’s obviously not something worth debating or even discussing. The point is that no matter what the changes in the diet, the biochemistry of fat loss is always the same, and it is the same for everyone. Everything is about insulin for the very simple reason that it is insulin that shuttles nutrients from the bloodstream into cells. This is true for sugar, protein and fat. But insulin is released by the pancreas primarily in response to the presence of sugar in the blood (but also in the absence of stress hormones which block insulin’s action to retain the sugar in circulation as long as the “potential threat” remains). The gist of it is: high insulin—nutrient storage, low insulin—nutrient release; high insulin—fat storage, low insulin—fat-burning.

What about the second colleague exercising and eating only 1500 calories that include starches and some fruit? He will continue to lose fat until the body determines that the bulk of the really excessive fat reserves have been spent, and then will stop. This will happen probably somewhere around 20% body-fat for guys and 30% for women, but will depend on age, exercise level, food, etc. So, he will get lean enough to appear slim, feel light, and also feel pretty good about himself every time someone compliments him on his figure. The more serious problem for him is that exercise, and especially the aerobic exercise like running that he is does to “burn more calories”, breaks down muscle quite quickly but it is not rebuilt.

The low calorie intake places the metabolism in calorie-deficit given that an average man needs about 1500 calories just for basic metabolic functions. This means that all additional calorie requirements have to come from somewhere other than the food that is eaten. Ideally, of course, these would come from fat reserves of which there are plenty; that’s the idea of the low-calorie dieter. But this will and can only happen if insulin levels are at rock bottom: I mean 1–3 units. Otherwise, the body will cannibalise its muscles because it can most easily get the easiest-burning cellular fuel it needs by converting protein into glucose. And the result? Over time he’ll lose most of his muscle, will retain that 15-20% fat, and will inevitably acquire the skinny-fat look. You know what I mean: the look of a slow, 40-50 year-old long-distance runner on a typical high-carb “runner’s diet” who looks skinny but giggly, with barely any visible muscle and no definition at all: muscle tissue broken down and not rebuilt; fat reserves not used because insulin is too high.

Had you guessed all that? Do you now understand how to burn fat without hunger and without losing muscle? Drop sugar levels, drop insulin levels: lose the fat reserves, keep the muscle. Eat fibrous veggies, lots of unprocessed fats and enough clean protein; don’t eat any sugar or starch. Very simple.

And here’s a teaser for a future series: if you want to build muscle and maximally slow down ageing, you will—in addition to this kind of shift in diet—also start lifting weights: squats and dead lifts, bench press and overhead standing press, bent-over rows, dips and pull-ups; and the heavier and more strenuous the better!

But if you’ve never done any of that, don’t go out and start lifting as much as you can right away because you’ll hurt yourself: you have to start slow, and have impeccable form and technique before starting to put on more weight. However, the fact is that there is really nothing more effective than heavy weight lifting to correct metabolic imbalances, postural problems, muscle and joint weaknesses; to burn fat, build muscle, and increase bone density; and totally rejuvenate the body and restore a incredibly youthful hormonal profile. The most amazing thing is that this is true for men and women of any age. I hope to find the time and write about this in the not-so-distant future.

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