The popular story of how low-carb diets work goes something like this: Reducing your carbohydrate...
Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...Tell Me More
For today’s edition of Dear Mark, I’m answering three reader questions. First, if things are going well on a relatively low-calorie intake, should you just keep on keepin’ on or should you increase food intake to “get ahead” of your needs? Next, what’s the deal with a study showing a high-carb diet is better for testosterone levels than a high-protein one? What does this mean for your Primal way of eating? And finally, can an improvement in heart rate variability after a carb refeed indicate a greater need for carbs?
For today’s edition of Dear Mark, I’m answering three reader questions. First, do anaerobic workouts—sprints, lifting, etc.—interfere with your ability to become a fat-burning, aerobic beast, or can you integrate them? Next, in last week’s post I talked a lot about glycogen depletion in the context of the “sleep-low” carb partitioning. How can we actually achieve this without doing the intense intervals the elite triathletes were doing in the study? And finally, does carb-fasting after strength training also work?
Thought experiment time. Say you train hard, hard enough to deplete a signifiant amount of glycogen. Your muscles are empty, sensitive to the effects of insulin, and screaming for a couple potatoes to refill glycogen. What do you do?
In most circles, the answer is to eat those potatoes and refill those glycogen stores. And why not? The post-workout period is a special window of opportunity for eating a bunch of carbs and having them go to the right places with minimal insulin required. They won’t contribute to fat storage. They’ll go straight to your muscles. Restocking glycogen sets your muscles up to repeat the hard work and keep up with your training. It makes sense.
What if you didn’t eat the potatoes after a hard workout? What if you abstained from carbs entirely after a glycogen-depleting workout? What if you just went to bed without any (carbs in your) supper? What if you were an elite athlete and skipped the carbs?
This isn’t a Homeric epic. There are no oracles laying out our destiny and predicting our inevitable demise. But even if we can’t know the precise date of our death, we can use certain biomarkers, measurements, and characteristics to make predictions—with a reasonable amount of accuracy—about a person’s propensity to kick the bucket.
As is the case with any observational data, these predictors may not be malleable. And if they are malleable, actively changing them won’t necessarily confer the longevity they’re associated with. Getting plastic surgery to appear younger probably won’t make you live any longer. But they do tell a story. They suggest the qualities, activities, behaviors, and exercise patterns that may, if maintained, lead to a better, longer life. At the very worst, walking a bit more briskly and gaining some lean muscle won’t hurt you, and it will very likely help you.
Are we shortchanging ourselves by complete elimination of potentially allergenic or sensitizing foods like wheat, peanuts, or dairy? Do we become even more sensitive to “bad” foods by avoiding them entirely? This question stems from two things I recently encountered. The first was a recent rewatcing of The Princess Bride. The second was the recent peanut allergy study.
If you haven’t watched The Princess Bride yet, go do it (the book is also good) because a small spoiler is coming. The hero Wesley spikes the wine he and the villain Vizzini are sharing with iocane powder, a fictitious ultra-lethal poison that kills instantly. But because Wesley has spent the last several years ingesting incrementally-larger doses of the poison, he has complete resistance to its effects. Both men drink. Only Vizzini dies. What else can this apply to? I wondered.
On a literal level, your metabolic rate describes how much energy you expend to conduct daily physiological functions. This has many practical ramifications, however, because your metabolic rate also influences how you feel, how many calories you burn, how many calories you can eat without gaining weight, your libido, your fertility, your cold tolerance, how much subjective energy you have, how you recover from injuries and stress, how specific foods affect you, and how you perform in the gym. In short, it’s usually a good thing to have a higher metabolic rate.
Here are a few ways to increase your metabolism in a healthy, productive manner.
For one of the 21-Day Challenge contests last week, you guys asked dozens of questions. Today, I’m answering a bunch of them in rapid fire style including how to get kids to eat more meat and veggies, how to get adults to eat greens, whether keto can coexist with high-carb, if it’s better to eat seasonally and many, many more. Don’t expect long, drawn-out answers. I’m answering quickly and succinctly. If you have any further questions after hearing the answers, toss ’em in the comment section. There will always be more Dear Marks down the line.
Let’s get to it:
Go back 160,000 years and we all share a common ancestor: The emergence of the first Homo sapiens in East Africa. Since then, humans have spread across every environment imaginable and adapted to those environments. Much remains the same. We all breathe oxygen, require protein, produce insulin, oxidize fatty acids. But extended stays in unique environments have created genetic proclivities in different populations. For example, descendants of people who settled in high-altitude areas like the Himalayas, the Andes, and the Ethiopian highlands tend to show greater resistance to low-oxygen environments, while the Greenland Inuit show unique adaptations to cold environments, including increased activity of heat-stimulating brown fat. And among the island-dwellers of Sardinia, where the landscape constrained the amount of available food, there’s considerable evidence of positive selection for short stature.
What other differences exist, and how can we explore them to inform and improve our own diet and lifestyle choices?
The popular story of how low-carb diets work goes something like this:
Reducing your carbohydrate intake lowers your insulin levels. Since insulin keeps fat locked into adipose tissue, lowering insulin can increase the amount of fat released to be burned for energy.
For the portion of the overweight/obese population with insulin resistance and chronically-elevated insulin levels, this is a fairly accurate description of why low-carb diets work so well. When you’re an insulin-resistant hyper responder in whom even a baked potato can cause elevated, protracted spikes in insulin that hamper fat-burning for long periods of time, or a person living under the backdrop of perpetually-elevated insulin, dropping the most insulinogenic foods can be your way out of obesity.
We know how important gut health is for overall health. We understand that it improves digestion, that our pursuit of extreme sterility has compromised our immune systems, and that the gut biome is etiologically involved in the pathogenesis of various health and disease states. We’re even familiar with the more esoteric functions of gut bacteria, like converting antinutrients into biovailable nutrients, synthesizing sex hormones and neurotransmitters, and mitigating the allergenicity of gluten. But what about gaining and losing body fat, the real reason most people get interested in diet in the first place—are the bacteria in your gut responsible for the fat on it?