Eat Real Food, Not to Excess
Principle one on my list is also the simplest to say and, for most of us, the hardest to actually live: eat real food, and not to excess. I want to spend some real time here, because two books changed how I think about this more than anything I learned in medical school — Ultra-Processed People by Chris van Tulleken, and Salt Sugar Fat by Michael Moss. If you haven't read either, I'd put both on your list. They were genuinely impactful for me, and I find myself referencing them with patients constantly.
What Even Is "Ultra-Processed"?
This is a surprisingly hard question to answer precisely, and even the researchers who study this argue about the exact lines. But here's a simple, practical filter I give patients: be suspicious of anything with more than five ingredients, or anything with an ingredient you can't picture as food. If a label lists something like maltodextrin, mono- and diglycerides, or sodium stearoyl lactylate, it's telling you something.
Chris van Tulleken, a physician and infectious disease doctor at University College London, makes the case in Ultra-Processed People that this stuff isn't really "food" in the traditional sense at all. It typically starts as a cheap, high-yield crop — corn or soy — that gets broken all the way down to its basic molecular building blocks, then chemically and physically reassembled into something that looks, smells, and tastes like food. It's less "cooking" and more "industrial engineering," and I think that reframing alone is useful.
He didn't just write about this from the outside, either. He ran a month eating no ultra-processed food, followed by a month eating roughly 80% ultra-processed food, and tracked what happened. By the end of the UPF month, he reported feeling anxious, exhausted, and achy, and he'd gained 13 pounds. He also points to four specific properties that make these products so easy to overeat: they tend to be soft, calorie-dense, heavily flavored, and full of additives — and people consistently rate them higher on food-addiction scales than they do real food.
The Deliberate Engineering Behind It
If van Tulleken's book explains what ultra-processed food is, Michael Moss's Salt Sugar Fat explains why it tastes so good — and it's not an accident. Moss, a Pulitzer Prize-winning investigative journalist, spent years inside the major food companies and found that salt, sugar, and fat are combined and calibrated with real scientific precision to create what food scientists sometimes call the "bliss point" — the exact combination that keeps you reaching for more.
This isn't a conspiracy theory. It's documented industry practice, and Moss lays out how companies use food science, marketing, and product placement — often aimed heavily at children — to build products that are, by design, difficult to stop eating. None of this makes any single snack "bad" in isolation. But it should change how you think about why some foods are so much harder to eat "just a little" of than an apple or a piece of grilled chicken.
Not to Excess, Either
The second half of this principle matters just as much as the first. Even genuinely good, whole food can be a problem in large enough quantities — portion and frequency count. But here's the encouraging part: when you're eating real food, your body's own hunger and fullness signals actually work the way they're supposed to. It's a lot harder to accidentally overeat a plate of vegetables, protein, and whole grains than it is to overeat a bag of something engineered specifically to make you keep going.
Here's a comparison I use in the office constantly: six tortilla chips are roughly equal, calorie for calorie, to one whole tortilla. Almost nobody would sit down and eat five tortillas before dinner. But eating thirty tortilla chips? That happens without a second thought. A third of a bag of tortilla chips runs around 600 calories — the same as eleven Oreos, a 12-ounce NY strip, or, on the other end of the spectrum, a genuinely enormous 12 cups of broccoli. Same calorie count, wildly different amount of actual food, and a wildly different experience of "fullness" along the way.
The same thing happens with foods that don't even feel like indulgences once they've been reworked. Nobody sits down and eats four sticks of string cheese. But bread it, fry it, and serve it with marinara, and suddenly it's an appetizer plate that disappears without much thought. The processing — and the format — changes how much we eat, even when the underlying food started out perfectly reasonable.
That's really the heart of "not to excess": it's rarely about willpower in the moment. It's about recognizing which foods and formats make overeating easy without you noticing, and which ones naturally keep you in check.
Three Practical Habits to Start With
I don't expect anyone to overhaul their entire pantry overnight, or to memorize the NOVA food classification system. Instead, I give patients three practical habits that do most of the work:
1. Shop the perimeter of the grocery store. Bakery, produce, meat, and dairy sit around the outer edges of nearly every grocery store in America, almost by design. The center aisles are where most of the ultra-processed products live. You don't have to avoid the center aisles entirely, but if the bulk of your cart comes from the perimeter, you're most of the way there.
2. Plan your week. A simple meal plan — even a rough one — is one of the most underrated tools in nutrition. It removes the moment of decision fatigue at 6 p.m. that so often ends in a drive-through or a delivery app.
3. Shop weekly, for that plan. Buy what the plan calls for, roughly once a week. This keeps your kitchen stocked with real food and reduces the number of times you're grabbing something processed simply because it's what's already in the house.
None of this requires perfection — and I'd be lying if I said I hit all three every single week myself. But these three habits, practiced consistently, do more for your long-term health than almost any diet trend I've seen come and go.
Next up, we'll dig into principle two: sleep, and why seven hours isn't really optional.
