Bioenergetics For Dummies (An Intro on Ray Peat)

Cold hands before anyone else’s in the room. Eight hours of sleep that doesn’t land. A body moving through the day like a system idling in the background, present but never quite here. Ray Peat spent close to five decades arguing that this has a physiology behind it, and that fixing it opens onto something most health advice never gets around to promising: warmth, curiosity, appetite for your own life, the feeling of being fully switched on.

Peat held a PhD in biology from the University of Oregon, specializing in physiology. Before that, in 1960, his master’s thesis was on William Blake, the poet who wrote that energy is eternal delight. That’s not a throwaway detail. Peat spent the rest of his career making something close to the same argument in the language of biochemistry: that a body running on enough clean energy doesn’t just survive, it has surplus to spend on being curious, warm, and awake to its own life. He also painted, kept an art gallery on his own website alongside decades of research and correspondence, and wrote until he died in 2022. The newsletters and articles he left behind, still free at raypeat.com, are the closest thing to a primary source for everything below.

Worth knowing before you go further: his framework runs against a lot of mainstream nutrition and endocrinology guidance, on saturated fat, on sugar, on how thyroid should be measured (hallelujah).

Peat’s central claim was that health isn’t a fixed state you either have or don’t. It’s an active process, something a body has to keep doing: rebuilding tissue, regulating water and minerals, holding its own shape against the pull of entropy. A cell isn’t a static structure sitting there. It’s spending energy every second to maintain its own form. Stop that spending and the structure collapses. Keep it going well and the structure gets easier to maintain, which runs against how we usually think about wear and tear.

This is why Peat kept coming back to the image of a healthy child: warm, curious, quick to heal, restless with energy that has nowhere urgent to go. A high, well fueled metabolism is what that kind of ease looks like in a body, at any age. His whole project was trying to figure out how an adult gets some of that back.

He split the fuel side of this into two rough categories. Oxidative metabolism is fuel and oxygen converted into energy cleanly, producing carbon dioxide as a byproduct, the kind of energy that feels steady and doesn’t run out by 3pm. Stress metabolism is adrenaline and cortisol propping up energy production when the oxidative system can’t keep up on its own. That second kind can carry someone for years. It can also be the reason a person looks driven, thin, and exhausted at the same time, running on energy that’s borrowed rather than earned.

Temperature and pulse were his two blunt instruments for telling which state you’re in. A waking temperature that’s low and slow to rise, a resting pulse on the low side, these were signs to him that the body was leaning on stress chemistry rather than steady fuel. He didn’t treat either number as gospel on its own. He treated the trend as information: track it for a couple of weeks, change something, see if it moves.

Thyroid hormone, in Peat’s view, is less a single number on a lab report and more the dial that sets how fast your whole system runs, how warm you are, how quickly you recover, how much appetite you have for effort. The liver plays a large role here too, since a large share of the conversion from inactive thyroid hormone (T4) into the active form (T3) happens there. A sluggish liver can mean sluggish thyroid conversion even when bloodwork looks fine.

This was one of his more contested positions. He argued that standard thyroid panels, especially TSH on its own, can miss tissue level hypothyroidism, a body running cold and slow while the numbers on paper say everything is fine. Mainstream endocrinology leans much more heavily on the lab numbers than Peat did.

The best known piece of Peat’s work is his stance on polyunsaturated fats, the kind found in sunflower, corn, soybean, canola, safflower, and similar oils. The chemistry isn’t in dispute: saturated fats lack the molecular structure that makes polyunsaturated fats so prone to oxidizing. PUFAs break down more easily when exposed to heat, light, and air, and once eaten, they get built directly into your cell membranes, the same structure Peat cared about protecting. There they can sit for years, making that structure more fragile rather than more resilient.

Research on linoleic acid, the dominant fat in seed oils, puts its half-life in human fat tissue at roughly one to two years, with full dietary turnover taking three to four years. If you’ve been eating a lot of seed oil for a long time, a clean week won’t undo it. This plays out over years.

His practical answer was to cook with saturated fats instead: coconut oil, butter, ghee, tallow. They’re more heat stable, and he saw them as directly supportive of thyroid function and cell structure alike, rather than simply neutral.

Peat didn’t fear sugar. He prioritized it, specifically the sugars in ripe fruit, honey, and milk, over starchy foods like bread, pasta, rice, and grains, which runs opposite to almost every popular diet framework right now.

His logic: glucose is the fuel your thyroid, muscles, liver, and brain run on most cleanly. Fructose, the sugar in fruit and honey, is largely processed by the liver rather than dumping straight into the bloodstream, which he considered gentler and more sustainable than a straight glucose or starch load. He was also cautious about starch and fiber more broadly, concerned that anything slowing gut motility could feed bacterial overgrowth and drive the kind of low grade gut inflammation that, in his view, keeps the whole system defensive and energy poor.

Inside his framework, a ripe orange was doing more for a body than a bowl of oatmeal: fuel that arrives easily, gets used cleanly, and doesn’t ask the gut to work overtime for it.

Peat’s protein advice was less about quantity and more about balance. Muscle meat alone is heavy in a few amino acids, tryptophan in particular, that he considered stress promoting and thyroid suppressing in excess. His fix was gelatin, the collagen found in skin, tendons, and bone, essentially free of tryptophan and rich in glycine, an amino acid he considered protective.

In practice, this meant eating the whole animal the way most cultures did before industrial muscle meat became the default: oxtail, shank, and bone broth, alongside eggs, dairy, and a moderate amount of muscle meat, rather than chicken breast as the centerpiece of every meal. A rough rule of thumb from his work is to aim for something like a third of your protein from gelatin sources, and not to skip liver and oysters when you can get them, both dense in nutrients he considered central to hormone production, and by extension, to feeling like yourself.

Ray Peat’s most specific recommendation is a plate of raw grated carrot dressed with a little vinegar and coconut oil, eaten on an empty stomach. The mechanism is mostly mechanical: the fiber in raw carrot isn’t digested, so it moves through the gut relatively intact, and along with the acid from the vinegar and the fat from the coconut oil, it’s thought to have a mild antibacterial and estrogen binding effect in the intestine. People who use it regularly tend to describe less bloating and a clearer head within a few days. An anecdotal pattern worth trying, not a clinical guarantee, and a strange enough little ritual to have survived this long if there weren’t something to it.

Peat was, famously, not against coffee. He considered it pro metabolic when paired with enough sugar to prevent the stress response that caffeine alone can trigger, and he drank a lot of it across his life. Salt was another one he defended when most of the wellness world was busy cutting it, on the reasoning that a body getting enough potassium alongside its salt has little to fear from either.

Beyond that, his list of supportive nutrients was short and mostly unglamorous: the fat soluble vitamins A, D, E, and K, along with calcium and magnesium. He wasn’t big on supplementation for its own sake, and he was skeptical of most commercial supplements, mainly because of fillers and poor sourcing. Food came first, always.

Strip away the specific foods and the whole framework comes down to one idea: a body with enough clean fuel doesn’t need to borrow energy from stress hormones to get through the day, and what it does with the surplus is where the actual life happens. Warmth, sleep, mood, patience, sex drive, how fast a cut heals, curiosity about things that don’t need to matter, Peat argued these aren’t separate systems you fix one at a time. They’re downstream of the same thing, the same capacity to generate and spend energy well.

He spent a career making something close to a biochemical case for what Blake had already said in four words two centuries earlier: energy is eternal delight. The goal, in his framework, was always more than getting enough fuel to function. It was having enough left over to feel something like delight in an ordinary day.

The useful question here was never the number on a thermometer. It’s what your own life would look like with energy left over at the end of the day, instead of only getting through it.