By now you should be over the hump of transition and well into the fat-burning zone. Now my goal is to provide you with guidelines and benchmarks based on my many conversations with experts on how to optimally repair your mitochondrial metabolism. It’s important for you to understand that this book is merely a starting point. In order to be successful over the long term, you will need to customize MMT to meet your individual needs and unique set of goals.
This is a critical step because MMT is much more than just a diet that you follow for a few weeks until you’ve lost some weight or stick to for a few months to reach some other goal before reverting to your former eating habits. Once you are physiologically fat adapted, this unique approach can be a lifelong way of living, especially when you integrate feast-famine cycling, which I explain in Chapter 10. The physical and mental benefits will keep motivating you to follow this healthy plan. All you need to do is stick with it.
There may be periods when it is more challenging to strictly adhere to the plan, and I will cover these situations later in this chapter. I am confident that once you experience how much better you feel when eating this way, you will likely be hooked for the long term. This chapter will cover how to make your fat-burning status a long-term part of your life.
THE DEFINITION OF BEING FAT ADAPTED
Let’s take a moment to define what it means to be fully adapted to burning fat. There are two levels.
1. Physiological Adaptation
When you first reduce your net-carb and protein intake and increase your consumption of healthy fats by following my instructions in the previous chapter, your body will naturally begin to burn more fat. It will also start converting some of that fat into clean-burning ketones that can in turn fuel most of the cells in your body, including your brain. When this happens, you are “in ketosis.”
It’s important to remember that it takes a while for your cells to adapt to using those ketones efficiently, as some of the enzymes required to break down ketones are different from those needed for glucose. So even though you are producing ketones when you first enter ketosis, your cells are not yet adept at using them for fuel because your body is not yet producing adequate amounts of the enzymes required to metabolize them. Adaptation can also take longer if you are older or insulin resistant or have high levels of circulating insulin, which can interfere with your ability to maintain a constant state of ketosis. If this is the case, expect it to take longer (months rather than weeks) for you to fully adapt to burning fat.
Your body needs to make other adjustments as well. As glucose levels drop, your muscles, which can already use fuels from several sources, will speed up the process at which they move fat into your mitochondria where it can be oxidized for energy. Your heart, which doesn’t utilize much glucose for energy under normal conditions, uses fatty acids for fuel but will add ketones to the mix just as soon as they become available.
Your brain is more selective because it’s protected by a special membrane called the blood-brain barrier, which doesn’t allow large molecules, including longer-chain fats, to cross into the brain. However, small ketones can readily pass through this barrier and are then shuttled into your brain tissue using special transporters. You already have some of these transporters, but you will make more as glucose levels drop and ketone levels rise. Your brain’s metabolic flexibility will gradually improve until it can harness 60 to 70 percent of its fuel from fat.
Maintaining your fat-burning ability helps keep these enzyme levels high and helps your brain tissue make better use of ketones. Because this adaptation is crucial to survival, brain tissue is able to ramp up production of the enzyme much more quickly than some other tissues. How long it will take your brain to maximize its use of ketones for fuel is difficult to predict and highly variable, depending on your age, your metabolic health, your genetic background, and your compliance with and response to MMT.
2. The Mental and Emotional Component
Becoming adapted to burning fat as your primary fuel is about more than your physiology. It also requires a shift in your thinking and an adjustment to your new lifestyle. Early on it might be hard to resist “sneaking” carbs, especially while you’re still experiencing hunger pangs or cravings for sweet or high-net-carb foods. You might also get derailed by holidays or travel plans. Over time, though, you will be better equipped to take these challenges in stride simply because you’ve established new eating habits and you’re firmly rooted in a new way of thinking about the connection between food and health.
You’ll also enjoy the benefits of eating a high-fat, low-carb, and adequate-protein diet, and experiencing these benefits will bolster your motivation to stay with the plan. In time, these changes will no longer feel overwhelming and instead will become your “new normal.” This shift in attitude and sense of yourself is an important part of the adaptation process, so be sure to give yourself enough time for this to play out
ANALYZE YOUR SUBJECTIVE DATA TO SEE HOW YOU’RE DOING
Your body is continually giving you feedback that can help guide you to your own personal fat-burning sweet spot. There is no one-size-fits-all food plan that will get you there. Although I have suggested guidelines for how much protein and net carbs to eat at each meal (see sidebar for a recap), you may learn you need to make some changes that are a better fit for your personal situation. For example, you might lower your intake of carbs, at least for now, to stay in a fat-burning zone, or end your daily fast closer to 13 hours than to 18 hours after your last meal.
Periodically assess the following areas, and use this feedback to tailor MMT to your needs and your body.
Hunger and Cravings
As you become fat adapted, your experience of hunger will change. Your appetite won’t be ruled exclusively by hormones such as insulin and glucagon, so you won’t crave those foods that were formerly like opiates to your receptors. And you are far less likely get a stomach-rumbling feeling of emptiness.
Although you will still have some awareness of the need to eat, the signal won’t have the urgency that comes when you are still relying on glucose as your primary source of energy. Remember: you experience the need to refuel when glucose levels drop and your brain responds by sending hormonal signals that demand your attention. This lack of urgency will in no way interfere with your enjoyment of food. You will still truly enjoy that delicious meal, but the physiological drive for it in any particular moment will not control your thoughts or actions.
If you do experience those old familiar sensations of hunger or weakness on MMT, it is probably due to one of these four conditions:
Energy Level
As you become adapted to burning fat for fuel, your energy will level out at a higher baseline than it was when you were burning glucose, which needed to be replenished every couple of hours. As your body makes more of the enzymes and activates other processes necessary to metabolize dietary fats and stored fats, you will have an astonishingly steady supply of energy that isn’t reliant on your immediate food intake. For that reason you can assume that the consistency of your energy levels is a sign that you are in a fat-burning zone.
If your energy levels are fluctuating, it could be an indication that you are bouncing in and out of fat burning. You may be inadvertently replenishing your glycogen stores, so take a good look at how many net carbs and grams of protein you’re eating. You may need to reduce those further in order to achieve consistent and long-term fat burning.
If your fatigue is sustained, refer back to Chapter 8 for information on a common culprit and how to remedy it.
If you happen to notice brain fog coming back while on MMT, check your food diary. Brain fog may be related to your food choices—eating too many net carbs or an excessive amount of protein could have cued an insulin response that has kicked you out of fat burning. If you haven’t been tracking, log a few days of your food intake on Cronometer.com and see if your macronutrient targets are being met.
Poor sleep is also a common cause of mental cloudiness, as are high stress and insufficient physical activity. Another factor that could be at play is a thiamine deficiency. A high-carb diet can lower brain levels of this B vitamin, which is used up when metabolizing glucose. Your brain is a glucose hog, using about 20 percent of body energy daily, and even more if you are doing strenuous mental work. Diabetics and alcoholics in particular are typically deficient in thiamine. Neurological symptoms of mild thiamine deficiency include memory impairment, fatigue, anxiety, apathy, irritability, depression, and poor sleep.
There is also a close connection between your gut and brain, so if you are experiencing brain fog, look for things that may impact the balance of your microbiome. Antibiotics can kill off beneficial bacteria, resulting in an overgrowth of disease-causing species that are destructive to both gut and brain health. Gut-disrupting medications, such as commonly prescribed proton pump inhibitors, are also responsible for upsetting this delicate balance. The chlorine in unfiltered municipal tap water can also impair your microbiome. Brain fog also might be due to a lapse in eating fermented foods or foregoing your probiotic supplements. Or it could be the result of a sensitivity or allergy to something in your environment. Histamine intolerance comes to mind. It could even be caused by a virus or post-viral syndrome.
Antibiotics and proton pump inhibitors can also interfere with the absorption of nutrients like B1, B6, B12, folic acid, calcium, magnesium, and zinc. All of these nutrients are required for normal brain function, and deficiencies in these nutrients can affect mental clarity.
You will likely notice a significant improvement in your digestion, with more regular bowel movements and less bloating and reflux as you continue to follow a fat-burning diet. There are multiple reasons for these phenomena. The quality of the foods you eat on MMT is much higher than that of the processed foods that make up the typical American diet. These foods contain more fiber, which acts as food for beneficial bacteria. In addition, pathogenic bacteria, such as H. pylori and yeast, feed on glucose, so when you dramatically lower your consumption of sugars, you increase the growth of beneficial bacteria. This in turn suppresses the growth of disease-causing bacteria by limiting their fuel source. In fact, a 2016 autism study confirms that you may notice a significant improvement in the health of your microbiome.1
If you notice digestive symptoms getting worse while following MMT, or are experiencing constipation, take a careful look at your food logs (or track your food intake for a few days if you haven’t been keeping regular records). Check in with your coach or health care provider for help with troubleshooting (and refer back to Chapter 8) to see if there are other explanations for what might be going on.
Chronic Conditions
The symptoms of many chronic conditions may ease up or disappear entirely as a result of the changes you make with MMT—refer to Appendix A for more specific information. This is because MMT improves mitochondrial metabolism and reduces systemic inflammation, both of which are often at the root of many chronic diseases. Be sure to work with your health care provider, as you may need to reduce or eliminate medications as your health improves. Remember: food is medicine.
Burning fat for fuel and providing your body with all its essential nutrients help you maintain your muscle mass even as you lose weight. An ideal situation is when all the weight you lose is fat rather than lean body mass. However, if you notice that you can’t seem to build new muscle even with regular workouts, or that you’re losing muscle tone despite eating what you perceive to be the right balance of macronutrients, it may be a sign that you need to increase your protein intake by 25 percent or even more on the days when you are doing strength training.
ALSO CONSIDER THE OBJECTIVE DATA
Balance the information you’ve gathered on how you’re feeling with these quantifiable measurements:
Blood Glucose Levels
Over time, you should see your fasting blood glucose levels trend downward, which is a great sign because it suggests that you’re giving your body a chance to regain its insulin sensitivity while also reducing systemic inflammation—two fundamental building blocks of good health.
If your glucose levels aren’t trending downward, or you experience substantial, unexplained inconsistencies from day to day, refer back for a list of possible reasons and remedies.
Ketones
Remember that unless you are addressing an ongoing chronic disease, you really only need to monitor your ketone levels in the first few weeks or months of your program, and then occasionally as a check on whether your plan is still working for you. Ideally, blood levels of ketones will range between 0.5 and 3.0 mmol/L.
I suggest checking your ketone levels either with a home blood ketone test or a breath meter tester like the Ketonix. I use a Ketonix to check my ketones every morning to confirm I am still in ketosis, even after feasting days of 150 grams of net carbs. Remember that being in ketosis is a signal that your body is burning fat for fuel.
As I covered in Chapter 2, ketones themselves aren’t the main reason why a high-fat diet has such a remarkable impact on metabolic health. It’s the nutrients you consume in combination with the times when you consume them that trigger multiple beneficial chain reactions. Ketones are merely a by-product of this process; using them as your primary gauge of success is a little like grading a student based on how many used-up pens and pencils you find in the trash. It’s about the inputs, not just the outputs—and all that happens in between.
Ketones are not the primary driver of health-promoting changes. You can make lots of ketones just from ingesting MCT oil, but unless you make changes to the rest of your diet, you will only experience a tiny fraction of benefits that a high-fat, low-carbohydrate, adequate-protein diet provides.
Your Weight—If Weight Loss Is a Goal
After the initial quick water weight loss that comes when you reduce insulin and deplete your glycogen stores (and release the water that is stored with glycogen), you will see your weight trend downward until you reach your ideal weight. That’s because a calorie isn’t a calorie when you are burning fat in the same way it is when you are burning glucose.
When you primarily burn glucose, your body stays mostly in fat-storage mode. But when you’re burning fat for your primary fuel, your body will convert some of those fats to ketones and excrete those that aren’t used through the urine. Insulin is the storage hormone and in MMT this mechanism isn’t triggered as often, so it becomes easier to maintain and even lose weight.
Also, as you burn more fat rather than store it, hunger pangs ease and you lose your cravings for processed and sugary foods, making fat loss easier to achieve. If you are already at a low body weight, you’ll need to make sure that you get plenty of calories from fat, enough to stabilize where you are, or even to gain a few pounds if that’s what you need.
In addition to tracking your total body weight over time, I suggest weighing yourself every few days at the same time of day, after your bowel movement in the morning and before you eat your first meal or drink any fluids. You’ll also want to update your estimate of body fat percentage; seeing it go down over time will help keep you motivated. (Refer to Record Your Starting Body Measurements for ways to do this.)
This will also help you keep tabs on your lean body mass, which you want to keep stable or even slightly increase over time. If you embark on a muscle-building workout regimen, expect your lean body mass to increase; when that happens you will need to increase your protein intake slightly. If you are eating a well-designed high-fat diet but your lean body mass declines over time, I suggest working with a health coach who is well versed in ketosis on fine-tuning your program or diet while keeping to the guideline of 1 gram of protein per kilogram of lean body mass. (I suggest working with a coach well versed in high-fat, low-carb, and adequate-protein diets, because most traditional fitness trainers overprescribe protein.)
Cronometer Records
Over time, recording what you eat in a typical day becomes one of the most powerful tools you have in keeping to your MMT plan. Recording your biometrics is another essential part of your recording.
Some people embrace the most intensive approach by weighing and tracking every morsel of food they put in their mouth by using Cronometer.com/mercola, while others are more reluctant to take the time to do so. To ensure that you stay on track with your diet, aim to record at least one typical day of eating and exercise each week.
Using Cronometer will help you comply with the diet because the thought of recording every handful of chips or piece of birthday cake can influence whether you choose to eat it. It’s also a continual learning tool that can help you identify which meals and foods provide the biggest bang for your nutritional buck. Using Cronometer on a regular basis will keep you from veering off track.
Cronometer can also help you assess your typical nutrient intake so you can easily see if there are any gaps you need to shore up with different choices or maybe even supplements.
You may find that over time, you need to restrict the amount of nonfiber carbs you are eating in order to improve on your fasting blood glucose, or that you can add more nonfiber carbs according to a feast-famine schedule, which I cover in Chapter 10, while still maintaining fat burning.
It’s also helpful to use Cronometer to track a few micronutrient ratios. In particular you’ll want to keep your eye on these ratios:
Omega-3 fatty acids are one of the best ways to counter inflammation because they provide your body with chemicals called resolvins. These remarkable substances turn off inflammation in your body when it is no longer needed to fight infections.
One caveat to keep in mind is that many have over-consumed fish oil and driven up their levels of eicosapentaenoic acid (EPA), a particular type of omega-3 fatty acid. When you take large amounts of EPA from supplements like fish oil, the level of arachidonic acid (AA) in relation to EPA can be driven down. When AA is low it can contribute to unstable cell membranes and bleeding. Life is a balance, and you need some AA for cellular structure, support, and signaling. For this reason, it’s best to get your DHA from seafood or whole seafood supplements like krill oil, not isolated extracted supplements like fish oils. Healthy seafood is a superior option to krill oil, but the oil is helpful when healthy seafood is not available. Krill oil is also far better absorbed because, unlike fish oil, it is in emulsified phospholipid form.
Potassium helps offset the hypertensive effects of sodium and helps your body maintain proper pH levels. In an article published in the New England Journal of Medicine in 1985, the authors evaluated the dietary intake of our Paleolithic ancestors to find they naturally consumed about 11,000 mg of potassium and 700 mg of sodium a day.2 This equates to nearly 16 times more potassium than sodium. Today that ratio is reversed: the daily potassium intake averages 2,500 mg and sodium 3,400 mg.
To bring your potassium intake up higher than sodium, prioritize the MMT-friendly foods that are high in potassium, including spinach, broccoli, Brussels sprouts, avocados, asparagus, nuts, and seeds. The ideal ratio of potassium to sodium you’re looking for is twice as much potassium as sodium. For most people this is about 5 grams of potassium a day. Please note that the potassium needs to come from sources such as vegetables, not potassium salts, to provide health benefits.
Magnesium also functions as a counterbalance to calcium—and too much calcium with too little magnesium can lead to heart attacks, strokes, and sudden death. Your target magnesium to calcium ratio is 1:1.
Luckily, magnesium is found in good amounts in many of the same foods that contain potassium, including leafy greens, nuts, seeds, broccoli, and Brussels sprouts, as well as cacao powder (good news if you’re a fan of chocolate fat bombs). The recommended dietary allowance for magnesium4 ranges from 310 to 420 mg per day, depending on your age and sex. However, I and many researchers believe we may need anywhere from 600 to 900 mg/day for optimal health.
If you aren’t meeting your targets for these nutrients, troubleshoot them sooner rather than later. Work with someone who can be objective, such as a coach who can review your food intake logs and blood test results and help pinpoint where you can make some improvements.
Perhaps 25 to 30 percent of people who adopt a high-fat diet will experience an initial rise in triglyceride and cholesterol levels. In others, the levels stay the same or even drop. There are a few factors to consider in deciding for yourself whether this should be a cause for concern:
If you do experience a rise in blood lipid levels or if you are confused or discouraged by a change in your lipid levels, please reach out to a health coach or other health care provider who specializes in high-fat, low-carb diets so you can get some objective insight into your situation before you give up on the plan.
Basic Guidelines for Optimum Fat Burning over the Long Term
These guidelines are a starting point and can vary widely based on your current health, health goals, and life circumstances. You will have to discover the benchmarks that work best for you.
Fasting blood glucose: Below 80
Ketones: Above .5 mmol/L, or consistently some shade of pink if you’re using urine test strips. If you are using the Ketonix breath instrument, if you see a flashing red light you know you are in ketosis; the more flashes, the deeper the level of ketosis.
Formula for determining protein needs: 1 gram per kilogram of lean body mass unless you are pregnant, breast-feeding, a competitive athlete, or elderly, as individuals in these groups may require additional protein.
Max amount of protein from both animal and plant sources in any one meal: 12 to 15 grams for most women (unless pregnant or nursing—then you may need more), 15 to 20 grams for most men.
MMT macronutrient ratios (may vary): 50 to 85 percent fat*; 4 to 32 percent carbs; 8 to 12 percent protein†.
Peak Fasting duration: 13 to 18 hours.
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* Once you are able to easily generate ketones, you can drop your percentage of fat calories to 50 percent and replace them with more net carbs from whole foods—not grains—so long as you retain fat-burning ability, measured by your ability to keep your ketone levels above about .5 mmol/L.
† The only time you’d want to consider increasing your protein levels above this suggested range is if you are strength training or otherwise aiming to increase muscle mass.