Metabolic flexibility is the capacity to match fuel oxidation to fuel availability—or switch between burning carbs and burning fat. Someone with great metabolic flexibility can burn carbs when they eat them. They can burn fat when they eat it (or when they don’t eat at all). They can switch between carbohydrate metabolism and fat metabolism with relative ease. All those people who can “eat whatever they want” most likely have excellent metabolic flexibility. So, why does it really matter, and how does it happen? Let’s get into the weeds today.
Consistency is key in everything we do.
Training in the gym: The most optimal workout imaginable won’t do a thing if you only get around to it once every two weeks.
Sleep: A solid 8 hours of shut eye every night beats 10 hours one night, 6 the next.
Learning a new skill: Practice for an hour each day and you’ll become a master. Spend twelve hours one time and never again, and you’ll remain a beginner.
The same is true for nutrition. A consistent, reliable way of eating—especially with a diet like keto, where extended consistency actually builds new fat-burning mitochondria and establishes habits—tends to produce the best results.
But what if you wanted to be a little less consistent? What if you wanted to cycle between Primal and keto? Is such a thing even possible?
Yes. Just make sure you do it right—and for the right reasons.
For today’s edition of Dear Mark, I’m answering a single, significant question. It concerns the latest “anti-low-carb” study claiming that we’re all killing ourselves by not eating bread. A reader wonders if the study is legit and if we should be worried about eating fewer carbs than “normal” people.
I don’t think we should be concerned, and I’ll explain why in detail. Let’s take a look and break it down.
For today’s edition of Dear Mark, I’m responding to four reader comments. First up, if a person can’t eat eggs, doesn’t like liver, but really wants choline, can they just supplement? Second, are a couple handfuls of almonds too much omega-6 for the average person? What if they eat fish? Third, a new study claims to show that keto dieting tanks hepatic insulin sensitivity. What should we make of it? Are we giving ourselves type 2 diabetes by going keto? And fourth, I highlight a great approach to drinking alcohol (and living in general) from one of our readers.
After my recent post on keto for women, I got a lot of feedback. One of the most common themes: “But what about menopause?” I heard from dozens of women in both the comment section and in emails who were having trouble losing weight and dealing with the varied symptoms of menopause. Was keto the answer? Was Primal? Were they doing something wrong?
Rather than start with the assumption that going keto or Primal is the best way to deal with menopause, I figured I’d start from ground zero, drawing on the extensive scientific literature on diet and menopausal symptoms to see if I could arrive at some general trends and make recommendations.
People go keto for many different reasons. Some want to get better at burning fat so they have a clean, reliable source of steady energy at all times. Some people are treating a neurodegenerative disease, or trying to prevent one from occurring in the first place. Others just want to lose body fat, take advantage of the cognitive effects of ketosis, or stop seizures. Those are all common reasons to go keto. Another reason people go keto is for the benefits to physical performance.