As I figured it would, last week’s post on fat-adaptation  generated a lot of comments and questions. I couldn’t answer all of them (maybe another time), so for today’s post, I tried to collate the most burning questions to arrive at a representative sample. That way I hit the major ones without making this one of those super long posts. If you feel I’ve missed any major ones, feel free to let me know in the comment section.
First up is the most basic of questions: how does one become fat-adapted? Some, probably most, of you have a good idea how to go about doing such a thing, but not everyone. And so, without further ado, let’s get to the questions:
How do I become fat-adapted?
Ramp up your fat intake. This will spur your body to increase fat-digesting enzymes that have likely laid rather dormant. Rather than consuming any old fat you can get your hands on, I’d stick to high-nutrient fat – from pastured animals , pastured egg yolks , butter from truly grass-fed cows , red palm oil , extra virgin olive oil  – and fat with interesting properties, like MCT and coconut  oil (which will ramp up ketone production). It will also “train” your mitochondria  to start burning fat for fuel.
Reduce your daily carb intake to about 50 grams if sedentary, 100-150 if you are highly active. Basically, you want to reduce your carb intake relative to your body’s demands.
Avoid lean protein. Eat protein that has fat attached, as a focus on protein (rather than meat, which has both fat and protein) could lead to your body converting excess amino acids to glucose .
Reduce your workout intensity. Don’t try to get fat-adapted while you try to make the CrossFit games, start P90X , do a triathlon , or engage in anything that demands a ton of glucose. It will end badly. Instead, walk a bunch  and occasionally lift heavy things . Once you’re fat-adapted, your desire to be active will likely spontaneously increase.
Aren’t ketones produced as a by-product of fat oxidation? Therefore, aren’t blood ketone levels the best way of measuring how good you are at burning fat?
To the first question, yes. It’s not an on-off switch. It’s not either-or. As biological systems, we are fluid things existing on continuums, and so we’re always using a mix of glucose, fatty acids, and ketone bodies.
Here’s a quick and dirty picture of how it works. In the liver during beta-oxidation, fatty acids are broken down into acetyl-CoA. Acetyl-CoA is oxidized and its energy is shuttled toward the production of ATP , the body’s energy currency. If “too much” acetyl-CoA is produced or insufficient amounts of a necessary precursor called oxaloacetate are present, however, the “excess” acetyl-CoA is converted into ketone bodies. So, as you can see, you could be beta-oxidizing fatty acids for ATP and producing ketones at the same time.
As to the second question, yes, I think that’s a fair statement. However, higher blood ketones isn’t necessarily “better.” If you’re under a medical professional’s care, using deep ketosis as a therapeutic tool to treat a serious medical issue (epilepsy, brain cancer, neurodegeneration), then yeah, shoot for maximum fat and ketone burning. But if you’re just a regular person who wants to maintain good body fat levels, be reasonably active, do some intense exercise now and then, and enjoy edible plant life, merely becoming fat-adapted is probably sufficient and ideal. Dr. Richard Veech, an expert on therapeutic ketosis, suggests  that “mild ketosis” is plenty. Mild ketosis describes the basic fat-burning state, the type that we typically wake up in after a night of “fasting.”
Once you are fat-adapted, how long does it take to become un-fat-adapted? If you go on vacation for a week and have a carbfest, do you have to start from square one?
Ideally, you’ll get to a place where you can have those days where things go off the rails  and bounce back without much of an issue – because the fat-burning machinery is in place, the mitochondrial biogenesis has already occurred, the digestive enzymes are upregulated and established. That’s where I am nowadays. I can have some ice cream, some roasted potatoes with dinner, a heaping bowl of fruit (hey, hey, not all at once), and I don’t miss a beat. But, if your 80/20 becomes more like 60/40  (and be honest, you know the difference), or you spend weeks or months with your old eating habits, that’s when the work you’ve done begins to stall or really turn around.
Still, I’d imagine that if you stick to a Primal Blueprint eating plan and avoid refined carbs and junk, you can do carb refeeds  after intense exercise and maintain stocked muscle glycogen  stores without affecting your ability to burn fat.
I’m confused…if you are a sugar-burning type, does that mean you won’t lose the weight until you become a fat-adapted type?
Not exactly, but fat loss will become vastly easier once you’re fat-adapted. The primary reason why diets fail is adherence. When you calorie restrict as a sugar-burner, you’re often up against an immovable, unrelenting force of nature: hunger. The very thing that you’re trying to overcome – your overconsumption of calories – is caused by the thing that thwarts you at every turn – your hunger. The hunger is the real problem, and it must be addressed, unless you like fighting regenerating hydra heads.
As I said last week, sugar  is a fleeting source of energy. Aside from the most superhuman of athletes, we simply don’t have a way to store large amounts of it in our bodies. Therefore, the sugar-burner needs to have a steady exogenous source on hand. Hunger is the body’s way of requesting energy when internal stores are depleted or inaccessible. If you’re constantly burning through glucose without ever really burning much fat, you’re going to be hungry, and you’re going to have trouble lowering the amount of energy you eat. If you’re able to access body fat for energy, you won’t get as insistent or frequent a hunger pang, because the required energy comes from within.
Since weight loss ultimately comes down to calories stored versus calories burned (more on this concept in a later post), and when you’re a fat-burner you’re both burning the stuff you want to get rid of (body fat) and taking in less energy and experiencing less hunger (because you’re eating body fat), being fat-adapted just makes losing unwanted weight easier.
When I lower my carb load to 50g (veggies and nuts) to kick-start fat burning I develop severe insomnia within a week. I produce no ketones, either. How can I break through this barrier? I know I’m not alone in this.
There are a couple ways to kickstart ketone production, if that’s what you’re after. You can increase your intake of medium chain triglycerides, as found in coconut products . Since MCTs don’t show up in cell membranes and never really appear in adipose tissue, they go directly to the liver to be converted into acetyl-CoA for energy. Remember how the acetyl-CoA-ATP pathway can be overwhelmed, thus spurring the creation of ketones? That’s what eating MCTs can do – increase ketone production . Use more coconut oil  and fewer long-chain saturated fats (which do go into cell membranes, can show up in adipose tissue, and are less likely to overwhelm the liver’s ability to make ATP), like animals fats, while you get adjusted.
You could also incorporate ketogenic amino acids. Huh? Well, a bit like how certain amino acids are more likely to participate in glucogenesis, certain amino acids are more likely to participate in ketogenesis. Both lysine and leucine  are readily converted into ketone bodies. As Paul Jaminet points out , high-leucine ketogenic diets have allowed researchers to treat epileptic patients without having to resort to the overly restrictive traditional ketogenic diets. Doing it this way gives you a little more leeway with your vegetable intake.
I would also make sure you’re getting enough minerals, especially sodium, potassium, and magnesium. Magnesium  in particular can help with sleep.
When you do eat your carbs, eat them closer to bedtime. A lot of people find that this helps with sleep , perhaps because a bolus of carbs can increase tryptophan , and subsequently serotonin, availability. Low-carb isn’t no-carb .
Well, that’s it for this time, folks. As I said earlier, send along any further questions you think I’ve overlooked and I’ll do my best to address them. Thanks for reading!