Professor 💯Dolf D💯

Older muscle needs more protein in a single meal to get the same building response as younger muscle. In older men, muscle building kept climbing with protein doses well past the point where it had already maxed out in younger men. Older muscle is less responsive to small amounts of protein, so a light meal that works fine for a 20-year-old may do very little for a 70-year-old. If someone is hoping to hold onto muscle with age, it's clear that each meal needs a generous serving of protein, and that need grows over the years.

Many people believe the brain needs a steady supply of dietary carbohydrate or it will stop working. The brain can run on more than glucose. In 1967, Owen and colleagues studied a small group of people who fasted for several weeks and measured what the brain was using for fuel. Ketones had replaced glucose as the brain's main energy source. When carbohydrate intake is low and insulin falls, the body starts pulling on stored fat. The liver turns that fat into ketones, which travel through the blood to the brain, where brain cells readily take them up and burn them for energy. This is a normal, built-in part of human metabolism. It also helps to separate two things that often get lumped together. Dietary carbohydrate and blood glucose are different. The liver and kidneys make glucose on their own, so the body keeps glucose in the blood even when someone eats no carbohydrate at all. That leaves an interesting question. Could brain tissue keep working if glucose were taken away completely and ketones were the only fuel on offer? In a paper I recently published with my BYU colleagues, we tested this in mouse brain tissue. We removed glucose from the environment entirely and supplied the ketone beta-hydroxybutyrate as the only outside fuel. The mitochondria in the brain tissue kept working. The tissue could also handle and recover from repeated, intense bursts of electrical activity that demand a huge amount of energy. Tissue given no outside fuel at all could not keep up. This was brain tissue studied in the lab over a short window, and living brains still need more study. Within that setting, ketones powered some of the brain's most energy-hungry work without any outside glucose. If someone worries that cutting carbs will starve the brain, it's clear that the brain is remarkably flexible about its fuel, and ketones are a fuel it uses very well.

I’d like to petition a modern art museum to put this up as a social commentary Caption: “Calorie-Controlled”

One of the reasons I focus so much on dietary carbohydrates is that no nutrient in the blood is as volatile as glucose. It can climb sharply within minutes of a meal and fall just as quickly. And as much as the blood sugar spike after a meal gets most of the attention, when it comes to hunger, the drop that follows may matter more. In a study of more than a thousand people wearing continuous glucose monitors, researchers looked at what happened to blood sugar in the hours after eating and how hungry people felt afterward. The size of the spike wasn't the best predictor of hunger. The dip was. Some people's glucose rose after a meal and then settled back to where it started. Others rose and then fell below their starting level about two to three hours later. That second group, the "big dippers," got hungrier sooner, ate their next meal earlier, and took in more calories over the rest of the day. This helps explain a common experience. Someone eats a breakfast of cereal, toast, or a pastry, feels fine for a while, and then by mid-morning is hungry again and looking for a snack. It isn't a lack of willpower. Their blood sugar went up quickly and then came down below where it began, and the body responds to that drop by pushing them to eat. It also shows why the same meal can affect people so differently. One person's glucose barely dips after a bowl of oatmeal, while another's crashes. This is one more reason a glucose monitor is so useful. It shows not only how high a meal sends your glucose, but how far it falls afterward. Meals built around protein and fat, with fewer refined carbohydrates, tend to produce a smaller rise and a gentler return, which means less of a dip and steadier hunger. If someone keeps feeling hungry a couple of hours after eating, it's worth looking at whether that meal is sending their blood sugar up and then down below where it started.

Older muscle needs more protein at a meal to get the same building response as younger muscle. When the two were compared, older men needed about 1.7 times as much protein per kilogram of body weight before muscle building reached its peak. This is part of why people lose muscle with age even when they think they're eating enough, because a serving that works fine for a younger person can fall short for an older one. After about 60, I'd aim for a generous serving of protein at every meal, roughly 30 to 40 grams for most adults, and I'd pair it with lifting.