The Truth About Seed Oils: Inflammation, Weight Gain, and What the Research Really Says
What did seeds ever do to you, huh?
They’re just tiny plant embryos wrapped in a protective coat, minding their own business, waiting for the chance to sprout into something green and photogenic.
Then humans showed up.
We grind them. We press them until they bleed. We bottle that liquid. We cook everything in it. Then we blame it for everything—from dad bods to brain fog. Seed oils went from “neutral pantry staple” to “chemical poison” faster than you can say “canola.”
But do they really deserve the hate?
What Are We Even Talking About?
Seed Oil = oil made by crushing the life out of seeds like:
Soybeans (soybean oil)
Corn (corn oil)
Canola
Sunflower
Safflower
Grapeseed
Cottonseed
They're ultra-processed, high in omega-6 polyunsaturated fats, and often used in:
Salad dressings
Chips
Baked goods
Anything that comes in a crinkly bag
Key point: They’re cheap, neutral-tasting, and everywhere.
“Bad for You” =
Let’s be specific. Specific is terrific, and clarity makes everything easier to understand
When people say seed oils are “bad,” they usually mean one (or all) of these:
They cause inflammation
They lead to obesity
They increase your risk of heart disease
They’re toxic when heated
They’re one molecule away from motor oil (cool story, bro)
But here’s the thing: Most of those claims are either overstated, taken out of context, or completely made up by shirtless guys on TikTok.
1. “They cause inflammation.”
📉 Verdict: Not in humans, eating normal amounts, in real life.
Yes, seed oils are high in omega-6 fats—specifically linoleic acid. No, that doesn’t automatically lead to inflammation. Meta-analyses in humans show that typical omega-6 intake doesn’t increase inflammation markers like CRP, IL-6, or TNF-alpha.
In fact, replacing saturated fats with polyunsaturated fats may reduce inflammation in some cases.
2. “They make you fat.”
📉 Verdict: Calories make you fat. Not seed oils.
Weight gain happens when you eat too many calories over time. Seed oils aren’t uniquely fattening—they just show up in foods that are easy to overeat: chips, fries, baked goods, etc. If seed oils were swapped into a well-balanced diet without a calorie surplus? You wouldn’t suddenly get love handles.
It’s not the oil—it’s the fact you ate 3 servings of chips without realizing it!
3. “They damage your heart.”
📈 Verdict: Actually, they might help it.
Large-scale trials (like the PREDIMED study and American Heart Association reviews) consistently show that replacing saturated fat with polyunsaturated fat (like from seed oils) lowers LDL cholesterol and reduces heart disease risk.
This doesn’t mean seed oils are some kind of heart-health superfood.
But in the context of a balanced diet—especially one that emphasizes whole foods, fiber, and omega-3s—they’re more likely to support cardiovascular health than harm it.
4. “They become toxic when heated.”
🤷 Verdict: Kind of—but so does everything else.
Here’s what people mean when they say oils become “toxic” at high heat:
When you heat oil too much, its molecules start to break down. This can create things like oxidized fats or free radicals—tiny unstable particles that might cause stress or inflammation in the body if you’re eating a lot of them over time. And yes, seed oils are less heat-stable than something like ghee or avocado oil, so they break down faster under extreme heat.
But this isn’t just a seed oil thing.
All oils—olive oil, butter, even coconut—break down if you overheat them or reuse them too many times.
If you’re concerned about oxidation, eating at home more often is never a bad call. You control the oil, the temp, and the ingredients—and not eating food from a fryer that’s been running since 10 a.m. Tuesday.
5. “They’re one molecule away from plastic/motor oil/poison.”
🙄 Verdict: So is water—if you play that game.
This is pure fear-mongering.
Saying something is “one molecule away” from a toxin sounds scary—but it’s scientifically meaningless without context. Chemical structure doesn’t equal danger. Water is one molecule away from hydrogen peroxide. That doesn’t make it toxic.
What actually matters:
👉 Dose
👉 Context
👉 How the body processes it
Let’s Talk Fats: Omega-6 vs. Omega-3
Here’s where the seed oil debate usually spirals: “Our omega-6 to omega-3 ratio is out of control! That’s why everyone’s inflamed and depressed!”
Hang on just a sec. Let’s break it down.
Yes, the typical Western diet is heavy on omega-6s (from seed oils) and low on omega-3s (from fatty fish, flax, chia, etc.). And yes, omega-3s—especially EPA and DHA—support heart health, brain function, and lower inflammation. So, improving that ratio is a smart move.
What to Do Instead of Panicking
Add salmon, sardines, or tuna to your week
Sprinkle chia or ground flax into yogurt or oats
Consider an omega-3 supplement (EPA/DHA), especially if you don’t eat fish
Don’t lose your mind if your hummus has sunflower oil
If you’re eating fatty fish twice a week (or supplementing with high-quality fish oil), your omega balance is likely just fine—even if you occasionally eat chips fried in soybean oil.
So... Are They Bad for You?
In most real-world diets, no—not inherently.
If your diet is mostly made up of whole, minimally processed foods
If you’re getting enough omega-3s from things like fish, flax, or chia
If you’re at a healthy weight and not living on deep-fried takeout
Then a little seed oil here and there? Not a problem. Especially in the small amounts most people actually eat.
Calling seed oils “toxic” oversimplifies a complex topic. It ignores context, dosage, and the bigger picture of how nutrition actually works.
The problem isn’t a drizzle of canola oil in your hummus.
It’s an ultra-processed diet, low in fiber, high in calories, and missing the fundamentals that truly impact your long-term health.
What’s Actually Worse Than Seed Oils?
You know what wrecks your health way faster than a drizzle of soybean oil?
Four hours of sleep
Living in fight-or-flight mode 24/7
Skipping cardio because you hate sweating
Drinking like you’re still in college
Eating like a raccoon in a drive-thru at midnight
We’ve got people worrying about the polyunsaturated fat content of their dressing—while sleeping five hours, skipping workouts, and pounding tequila like water on weekends. C’mon folks!
Don’t major in the minors.
Final Word: What Actually Deserves Your Attention
Seed oils aren’t killing you.
If your diet is mostly whole foods, you’re getting enough omega-3s, and you’re maintaining a healthy body weight, seed oils aren’t a major concern—especially in the amounts most people consume. Could you swap them out for olive oil or avocado oil sometimes? Sure.
But let’s be real: most people have bigger fires to put out.
Before stressing about salad dressing, focus on what actually moves the needle:
Eat more protein—especially at breakfast
Move more—yes, walking counts
Sleep better—start by going to bed 30 minutes earlier
Drink less—not zero, just less
Manage stress—deep breaths beat doomscrolling
If your house is on fire, fix the flames before repainting the walls. Seed oils aren’t toxic. They’re just not the thing holding you back.
Fix the big rocks first.
Then - and only then - can you argue about canola oil.
Best,
John
P.S. With my online fitness coaching, I cut through the noise (like seed-oil fear) and get you the results that matter—more energy, less fat, more muscle, lower disease risk. Just like Joe, Rob, Jonathan, and dozens of others I’ve coached.
P.P.S. I showed up late to my cousin’s bachelor party in Scottsdale this weekend. Missed the river tubing—but walked into an empty house, a giant TV, and college football already on. Could’ve been worse!
3 Steps You Can Take
Apply for coaching - If you’re ready to start, you can fill out a coaching application here (it takes 90 seconds or less). Best case, you change your life. Worst case, I’ll help you draw up a road map to get closer to your goals.
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Keep learning - You can check out my other articles here. Nobody asked me to, but I’ve spent a ton of time researching everything from artificial sweeteners to saturated fat to testosterone and more, so you don’t have to.
