How Polyunsaturated Fats (PUFAs) Impair Metabolism and Energy Production
Together let's understand why the PUFAs in seed oils (and high intakes of conventional pork/chicken/eggs) can change how your body makes energy.
The first thing to understand is that not all dietary fats are created equal.
The composition of the fats we eat matters, a lot, especially when it comes to energy production. (Meaning, the amount of saturated, monounsaturated and polyunsaturated fat).
Energy production is the core of metabolism. It’s the process of converting the macronutrients you eat (carbohydrates, fats, and protein) into ATP, the usable energy currency of your cells.
And quite simply: the more energy your body can produce, the better it functions.
Think of energy like a bank account.
When you have plenty of money in the account, you can spend freely. You can invest, build, repair, and thrive.
But when funds are low, you cut back. Only the most essential expenses get paid.
Your body works similarly.
When energy production is robust, your body can support strong digestion, healthy hair and nails, warm body temperature, resilient tissues, & more.
But when energy production drops, the body shifts into survival mode.
Essential functions, like heartbeat, breathing, and vision, are prioritized.
Non-essential functions, like optimal digestion, fertility, skin health, and hair growth, are downregulated.
This is why early signs of metabolic stress often show up in the most vulnerable tissues first. (And why it will differ person to person)
A downregulated metabolism lowers energy output as a protective mechanism. You can't push when there isn't enough fuel in the tank.
But that protection comes at a cost: suboptimal health.
To understand how dietary fats influence this process, we need to zoom in to the cellular level.
Fat Structure Matters
Saturated fats and unsaturated fats have different molecular structures, so of course the body processes them differently. (And yes, there are different types of saturated and unsaturated fats).
But when it comes to energy production, higher-PUFA diets create significant disruptions.
Why?
There are multiple layers to this, but it starts with oxygen availability.
A strong metabolism depends on efficient energy production, and that process is highly dependent on oxygen availability at the cellular level.
When oxygen availability is high, the body can rely on oxidative phosphorylation: the most efficient, oxygen-based energy pathway that produces large amounts of ATP, and low levels of lactate (metabolic suppressor).
But high-PUFA diets interfere with this process.
How PUFAs disrupt oxygen availability
Polyunsaturated fats are chemically unstable and prone to oxidation. As a result, the body must use valuable oxygen (ref, ref) to:
- - Process excess PUFAs
- - Manage lipid peroxidation
- - Detox and eliminate oxidized fatty acids
This increased oxygen demand leaves less oxygen available for optimal ATP production.
As oxygen availability drops, the body adapts by shifting away from oxidative phosphorylation and toward glycolysis, a backup, fermentation-based pathway that produces far less ATP and generates more lactate relative to the preferred pathway (oxidative phosphorylation).
In short: higher-PUFA diets consume oxygen, leaving less available for robust energy production.
This shift lowers energy efficiency, suppresses metabolic rate, and ultimately reduces the body’s ability to burn fuel effectively.
This is one of the key reasons seed oils or high PUFA consumptions can hinder health over the long term.
What the Research Shows
Let's assess a key study to better understand what's happening at the cellular level.
Seed oils are high in polyunsaturated fats (PUFAs) and low in saturated fats.
To better understand how this impacts metabolism, let’s look at a key controlled animal study comparing saturated fats to PUFAs (here, Omega 6 Linoleic Acid).
In this study, calories were the same, but the type of fat differed between the saturated group and PUFA group.
The results were striking!
1. Impaired Mitochondrial Energy Production:
The PUFA group showed impaired mitochondrial function, including a documented decrease in citrate synthase (CS) activity.
Citrate synthase is a key enzyme in the Krebs cycle and is commonly used as a marker of mitochondrial capacity.
Lower CS activity indicates reduced mitochondrial content or efficiency, and a diminished ability to generate ATP through oxidative metabolism.
In other words, the PUFA-fed animals had less capacity to produce energy at the mitochondrial level.
2. A Shift to the Less Efficient Energy Pathway
The PUFA group also showed a significant metabolic shift:
- - Increased reliance on glycolysis
- - Decreased reliance on oxidative phosphorylation
As glycolysis increased and oxidative phosphorylation decreased, ATP production falls and lactate production rose, both of which suppress metabolic rate.
LDH = lactate dehydrogenase
CS = citrate synthase
ODADH = beta-hydroxyacyl coenzyme-A dehydrogenase
3. More Fat Storage and Weight Gain
A suppressed metabolic rate means fewer calories burned at rest.
So even though both groups consumed the same number of calories (actually, the saturated fat group ate slightly more), the PUFA group had greater weight gain and more fat storage.
This isn’t mysterious, the PUFA group had a lower energy output ("calories out" side of the calories in vs calories out equation).
When energy production is impaired, the body adapts by storing fuel instead of burning it.
4. Fat Accumulation and Glycogen Depletion in the Heart
There was also a difference in the heart tissue composition. The PUFA group had increased fat storage and decreased glycogen concentration in the heart.
This is especially concerning because cardiac glycogen plays a protective role during hypoxic (low-oxygen) emergencies. Lower glycogen reserves reduce the heart’s resilience under stress.
And having more stored fat in the heart is never a good thing!
5. Increased Oxidative Stress
Finally, the PUFA group exhibited higher levels of lipid peroxidation: a direct consequence of PUFA instability.
The researchers concluded:
“We were able to show that diets rich in PUFAs were deleterious as compared with SFAs in the heart by providing cardiac susceptibility to lipoperoxidation and shifting the metabolic pathway for energy production.”
And:
“Diets rich in PUFAs may be disadvantageous because they can lead to the highest cardiac oxidative stress.”
And:
“The type and structure of lipids ingested can have very different metabolic consequences.”
Something that's important to point out is that even the “saturated fat” group in this study consumed 18.88% PUFA, which is still quite high!
So, would the metabolic outcomes have been even better if PUFA intake had been kept lower?
What This Means Long Term
The takeaway is clear: not all dietary fats are the same.
The fatty acid composition of the fats we consume directly impacts energy production, metabolic rate, and long-term health.
Yes, this study was done in mice, and that’s appropriate for mechanistic research.
Controlled feeding studies in humans are extremely difficult, expensive, and ethically complex.
You can’t lock humans in a lab and control every variable for weeks at a time.
That’s why animal models are essential for understanding what’s happening at the cellular level.
And context matters.
Humans historically consumed diets higher in saturated fats and far lower in PUFAs. There is no historical precedent for diets as PUFA-heavy as modern seed-oil-rich diets.
Now of course, PUFAs aren’t the only contributor to today’s metabolic dysfunction (sedentary lifestyles, for example, play a role) but they are a meaningful contributing factor.
By interfering with energy production, excess PUFAs keep the body in a survival state: conserving energy, storing fat, and downregulating non-essential functions.
Thriving requires energy.
And energy production changes based on the fats we choose.
This is Why we Do What we Do at Nourish Food Club
The reality: the food system has been PUFAd.
Yes, PUFA rich seed oils have replaced traditional animal fats richer in saturated fats.
But now livestock are eating PUFA rich feed due to industrial agriculture, so the fatty acid composition of eggs, pork, and chicken are higher than ever before in human history.
Understanding how dietary fats impact energy production changes the way you see food. It’s not just about calories, macros, or labels: it’s about whether the food you eat supports efficient metabolism and resilient health.
At Nourish, we custom formulate our own Low PUFA livestock feed, and we intentionally source food from our partnership of small regenerative farmers who prioritize what animals eat, how they’re raised, and the quality of fat produced as a result. That means avoiding unnecessary seed oils, limiting excess PUFAs, and choosing fats that align with how the human body actually produces energy.
The result: lab-tested Low PUFA eggs, Low PUFA pork, and Low PUFA chicken.
Food that supports energy production, metabolic flexibility, and long-term health rather than quietly working against it.
When you choose Nourish Food Club, you’re not just buying food. You’re participating in building an alternative food system with us: one that values transparency, regeneration, and food you can truly trust.
>> Join Nourish Food Club Today and Access Traditional, Low-PUFA Food
