You Don't Need to Cut Carbs
I'm getting my master's in Nutrition & Dietetics at UC Berkeley, and here's what I'm learning about carbs.
You don't need to cut carbs. You need to understand them.
Carbs are the first thing most of us are told to cut, and the thing we're taught to fear. But the deeper I get into my program, the clearer it becomes: the problem was never carbs. It's that no one taught us how our bodies actually use them.
So I pulled the most useful things I'm learning into twelve simple ideas: how digestion really works, from the first smell of your food all the way down to your gut. None of it is about restriction. All of it is about working with your body instead of against it.
1. Nutrients in food are almost never in an absorbable form
Nutrients in food are almost never in an absorbable form. They're packaged the way the plant or animal needs them, so digestion is a process of unpacking. How you eat, pair, and prep your food shapes how easily your body can unpack it.
Why does digestion take so much work? Nutrients in food are almost never in a form your body can absorb. They're packaged the way a plant or animal cell needed them, like starch locked inside a seed's tough cell walls to feed a new plant.
Your GI tract, your whole digestive system from your mouth to your colon, exists to take those packages apart into pieces small enough to cross into your body. For carbs, that means breaking starches and sugars down into single sugars your body can absorb.
Why does this matter? You can help your body digest your food at every step. Soaking, sprouting, and cooking begin the unpacking in your kitchen, slowing down and pairing your carbs with the rest of the Core Four carry it through at the table, and your body gets started even before your first bite.
2. Digestion starts before you eat
Digestion starts before you eat. Smelling or even thinking about food signals your brain to get your saliva flowing and your stomach primed. So take a second to see and smell your food before your first bite.
Ever start drooling just walking past a bakery? That's not random. The second you see, smell, or even think about food, your brain's sensory and emotional centers pick it up and pass it to a control center in your brainstem. From there, your parasympathetic nervous system, the part of your nervous system that runs involuntary functions like digestion while your body is at rest (often called "rest and digest"), carries the signal to your salivary glands, and your saliva starts flowing.
The same kind of brain signal, carried by your vagus nerve, helps get your stomach primed to make acid. This is called the cephalic phase, and it's a real reflex. The reason it exists is timing. Enzymes and acid take time to reach working strength, so priming the system means your food meets a moistened mouth and a ready stomach to land in.
Why does this matter? It's a good reason to slow down a bit at meals. If you're eating at your desk or scrolling through your plate, you may be skipping part of this prep. No need to make every meal a ceremony, but taking a moment to look at and smell your food can help your body get ready for it.
3. Eating fast is harder on your digestion and your appetite
Eating fast is harder on your digestion and your appetite. Your saliva starts breaking down carbs while you chew, and your fullness signals need time to kick in. Slowing down gives both a chance to work. Even a small pause between bites helps.
Ever finish a meal and realize you barely remember eating it? That speed matters for both your digestion and your appetite. Your saliva contains an enzyme called salivary amylase that starts breaking down starchy carbs, like bread, rice, and pasta, as soon as they hit your mouth. Chewing helps it along by breaking food into smaller pieces and mixing it with saliva, so the enzyme has more to work with.
When you eat fast, your food reaches your stomach in bigger pieces, with less of a head start. Once it's there, stomach acid shuts that enzyme down, and the rest of your gut picks up the work.
Your appetite needs time too. As food reaches your small intestine, your gut releases hormones, including GLP-1, that tell your brain you're getting full. Those signals take time to build, so when you eat quickly, you can finish your plate before they catch up.
Why does this matter? When we think about gut health, we usually think about what we eat, not how we eat it. No need to count your chews, but setting your fork down between bites, or sitting down to eat instead of snacking on the go, gives your saliva and your fullness signals time to do their job.
4. Soaking and cooking start the unpacking for you
Soaking and cooking start the unpacking for you. Heat and water soften tough cell walls, cut down the sugars that cause gas, and switch off compounds that upset your stomach, so you get more from grains and legumes with less bloating. A little prep goes a long way.
If beans or whole grains have ever left you gassy or bloated, prep might be the missing piece. Grains and legumes are seeds, built to protect the food supply inside them. Their carbs sit behind tough cell walls, alongside natural compounds that help protect the seed.
Soaking is the first step. It shortens your cooking time and pulls out some of the sugars in legumes that cause gas, which is why you drain and rinse them. Then heat finishes what the water started. Cooking softens those tough cell walls so your body can reach the carbs inside, and it switches off anti-nutrients, compounds in raw grains and legumes that can upset your stomach and make protein harder to digest. Boiling dried beans for at least 30 minutes, or using a pressure cooker, takes care of most of them.
Why does this matter? Preparing your grains and legumes well means you can enjoy more of them, and all the fiber that comes with them, with less discomfort. Soak and rinse when you can, and cook them until tender. Short on time? Canned beans count too, since they're already cooked. Just give them a rinse.
5. Pairing your carbs reduces the blood sugar spike and supports energy
Pairing your carbs reduces the blood sugar spike and supports energy. Protein, fat, and fiber slow the absorption of carbs, which helps you feel fuller and prevents the crash after you eat. That's the Core Four pairing at work. Add at least one to your carb-heavy meal.
Ever notice that toast on its own leaves you hungry an hour later, but toast with eggs and avocado holds you over? Protein, fat, and fiber are the reason. They slow how quickly carbs are absorbed, so sugar reaches your blood more gradually. Part of that happens in your stomach, since what's in your meal affects how fast your stomach empties into your small intestine, where most carbs are absorbed.
Protein also helps in another way. It buffers some of your stomach acid, which lets your saliva's carb-digesting enzyme keep working a little longer. So the same pairing that slows absorption also gives your digestion a bit more of a head start.
Why does this matter? What you eat with your carbs changes how they work for you. Fruit with nut butter, toast with eggs and avocado, rice with chicken and vegetables: each one turns a carb that could leave you hungry into a meal that holds you over. It's exactly why the Core Four puts protein, healthy fats, and fiber on every plate.
6. Fiber is the part of plant foods your body can't digest but needs
Fiber is the part of plant foods your body can't digest but needs. It's a type of carb found in fruits, vegetables, whole grains, and beans. Instead of breaking down into glucose, it moves through your gut, keeping you full, slowing how fast sugar is absorbed, and supporting regularity. The key is to make room for it at every meal.
Take a look at any nutrition label, and you'll see fiber listed under carbohydrates. That's because fiber is a carb. It's built from sugar building blocks, but they're linked in a way your digestive enzymes can't break, so it passes through.
As it passes through, fiber gets to work. In your stomach, it adds bulk that helps you feel full. In your small intestine, it can slow how fast sugar is absorbed. And in your colon, it feeds your gut bacteria and keeps you regular. Fiber's benefits come from the fact that it isn't digested.
Why does this matter? It changes how you look at carbs. A high-fiber food has fewer digestible carbs than its total carb count suggests, because the fiber isn't broken down into glucose. There's a name for this: "net carbs." It's your total carbs minus the fiber, which tells you how many carbs your body actually digests.
7. Fiber comes in two types, and you need both
Fiber comes in two types, and you need both. Soluble fiber (chia seeds, oats, beans) forms a gel that keeps you full and slows glucose absorption. Insoluble fiber (whole grains, nuts, leafy greens) adds bulk and keeps things moving. Try mixing both into your day.
A bowl of overnight oats with chia, Greek yogurt, nuts, and berries can keep you full for hours, and soluble fiber is a big part of why. Found in oats, beans, chia seeds, apples, and flaxseed, soluble fiber dissolves in water and forms a gel that slows how quickly your stomach empties and how fast sugar is absorbed.
Insoluble fiber works differently. Found in whole grains, nuts, seeds, and vegetables like leafy greens and green beans, it doesn't dissolve. It adds bulk and pulls water into your colon.
Why does this matter? Together, they cover both sides of digestion: soluble fiber keeps you full and steady, and insoluble fiber keeps you regular. Most plant foods have a mix of both, so eating a variety of fruits, vegetables, whole grains, beans, nuts, and seeds covers you.
8. Your gut bacteria turn fiber into fuel for your colon
Your gut bacteria turn fiber into fuel for your colon. Fermenting it creates short-chain fatty acids like butyrate, the main energy source for the cells lining your colon, so the fiber you can't digest still fuels you.
So where does fiber go after it passes through? It ends up in your colon, home to trillions of bacteria across thousands of species. Food spends just a few hours in your small intestine, but two to three days in your colon, and that time is exactly what your gut bacteria need. They ferment fiber, breaking it down in a way your body can't, and make compounds called short-chain fatty acids, along with some gas.
One of those, butyrate, is what the cells lining your colon run on. The others are absorbed and put to use by your liver. Feeding your gut bacteria fiber also helps the helpful ones grow, and they even make small amounts of vitamin K and some B vitamins.
Why does this matter? Every time you eat fiber, you're feeding your gut bacteria, and they're feeding the cells that line your gut. Building fiber into each meal is one of the simplest ways to take care of your gut.
9. Your gut bacteria need time to adjust to more fiber
Your gut bacteria need time to adjust to more fiber. A sudden jump means more fermentation and more gas, so add fiber slowly and drink more water to help it do its job.
Feeling gassy or crampy after eating more fibrous foods? That's fermentation at work. When fiber reaches your colon, your gut bacteria break it down, and gas is a natural byproduct. When you add a lot of fiber at once, your bacteria suddenly have much more to ferment than they're used to, so they make more gas. Going slow gives them time to adjust.
Water matters too. Fiber holds onto water as it moves through your gut, and that's what keeps things soft and moving. Soluble fiber turns water into a gel, and insoluble fiber pulls it into your colon to add bulk. When you add fiber without adding water, there's less for it to work with, which can leave you feeling backed up.
Why does this matter? If you're jumping on the fibermaxxing trend, slow and steady is the way to go. Add a little at a time, drink more water as you go, and give your gut a few weeks to adjust.
10. Prebiotics and probiotics aren't the same thing
Prebiotics and probiotics aren't the same thing. Prebiotics feed the bacteria you already have, and probiotics add live ones. Eat fiber-rich foods to feed them, and fermented foods like yogurt to add more.
Ever wondered if you should be taking a probiotic? It helps to know the difference first. Prebiotics are foods your body can't digest that feed the helpful bacteria already living in your gut, like the fiber we just covered. Probiotics are live bacteria, like the Lactobacillus in yogurt and other fermented foods, that add to your gut community.
Your gut bacteria work as a team. Some break fiber down into sugars, and others eat those sugars right away, which keeps harmful bacteria from getting a foothold. When that balance gets disrupted, like after a round of antibiotics, sugars that would normally get eaten up start to build up, and harmful bacteria use them to grow. One of the best ways to keep things in check is to keep your good bacteria well fed, so they can hold their ground.
Why does this matter? Food is your everyday tool for a healthy gut community. Keep both on your plate regularly, and lean into them even more after a round of antibiotics.
11. Your leftovers can be doing your gut a favor
Your leftovers can be doing your gut a favor. As cooked potatoes, rice, and bread cool, some of their starch turns into resistant starch, which feeds your gut bacteria the way fiber does. Don't fear leftovers, and freeze your bread!
Not everyone loves leftovers, but here's some good news that might change minds. Starch is packed into tiny granules. When you cook it, water gets in and the granules swell and loosen up, so your digestive enzymes can reach the starch easily. As cooked potatoes, rice, or bread cool, some of that starch tightens back up into a structure your enzymes have a harder time breaking down.
That tightened-up starch is called resistant starch. Your body can't fully break it down, so it passes through like fiber and feeds the bacteria in your colon, which makes it a prebiotic. And since it isn't digested, less of it turns into glucose.
Why does this matter? It's an easy win for meal prep. Cook potatoes or rice ahead, let them cool in the fridge, and enjoy them cold in potato salad, grain bowls, or wraps through the week. Bread gets in on it too: freeze it, then toast it straight from the freezer.
12. Let carbs work for you, not against you
Let carbs work for you, not against you.
Every carb you eat comes packaged, and your body works from the first smell all the way to your colon to unpack it. What you can digest becomes energy, and what you can't goes on to feed your gut.
Here's what to take with you:
Slow down and chew, so your digestion gets its head start.
Pair your carbs with protein, healthy fat, and fiber for fuller, steadier energy.
Soak and cook your grains and legumes, and let potatoes and rice cool for a gut-friendly bonus.
Feed your gut a mix of fibers and fermented foods, starting slow and staying hydrated.
Here's what I keep coming back to: you don't have to fear carbs or cut them out to feel your best. You just have to understand what your body is doing with them, and give it a little help along the way.
This is the first of my nutrition-school notes, and there's a lot more to come. Stay tuned!
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Xo, Mo
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