When is a Low-Fat, High-Carb Diet Good?

I’ve been exploring ways to add more butter to my diet. Butter from grass-fed cows is an anti-obesity and longevity superfood, and I get mine shipped from an Amish farm in Pennsylvania. I’m excited that May butter will be available soon, made from the nutrient-rich yellow milk produced by cows when they start grazing on fresh green pasture instead of winter hay.

The problem with butter is that it pairs with carbs — bread, potatoes, even noodles — which I try to minimize on my keto diet. My solution, which I got from ChatGPT actually, is to eat chunks of butter wrapped in slices of roast beef.

Now I know some of my readers just cringed. It’s hard to shake the 50+ years of low-fat, high carb propaganda literally shoved down our throats. Regardless, an ancestral ketogenic diet, high in animal protein and fat, is now the model for healthy eating. Even the U.S. government updated its food pyramid more than a decade ago to elevate the importance of animal protein and redeem saturated fat.

Nevertheless, the advocates of a low-fat, high carb diet — the compromised researchers and captured regulators — were superficially right, albeit for the wrong reasons. Under certain conditions, now commonplace, a keto diet does in fact do more harm than good.  

The link between sunlight and the TCA cycle (Krebs cycle)

A ketogenic diet shifts your metabolism to burn fat for fuel instead of carbohydrates. This shift is useful because in the TCA cycle, mitochondria generate significantly more ATP (energy) per molecule of fat compared to carbs. Because the root cause of modern disease is underpowered mitochondria not producing enough ATP to meet the energy demands of the cell, we should be maximizing mitochondrial output of ATP.

But here’s the trick. According to quantum biologist Dr. Jack Kruse, your body’s ability to efficiently run the TCA cycle is highly dependent on circadian alignment and sufficient sun exposure.

Circadian rhythm

The suprachiasmatic nucleus (SCN), located in the hypothalamus, acts as the body’s master clock. It uses the input of morning sunlight on the eyes to synchronize biological rhythms. When your circadian clocks are optimized, metabolic processes run more efficiently.

For example, according to one landmark study, your liver’s ability to burn fat (beta-oxidation) is tightly linked to your body clock. In every cell in your body that contains mitochondria, the proteins that facilitate fat burning will be less active in the absence of morning sunlight.

The beta-oxidation process is especially critical for an efficient TCA cycle. Your body uses beta-oxidation to break down fat into smaller units called acetyl-CoA. These molecules are used to produce ATP in the mitochondria via the TCA cycle.

Heme protein optimization

According to Dr. Kruse, morning sunlight — rich in red and near-infrared wavelengths — helps iron maintain its reduced Fe²⁺ state, which is critical for the proper function of heme proteins. Fats yield significantly more total ATP than carbs through the TCA cycle, but they require more oxygen to burn.

While the TCA cycle doesn’t use oxygen directly, it relies on oxygen-dependent electron transport to recycle the cofactors needed for continued ATP production. Hemoglobin (a heme protein) in red blood cells uses Fe²⁺ to carry oxygen to tissues, which is essential for the broader process of cellular respiration, including the Krebs cycle. Cytochrome c oxidase (another heme protein in mitochondria) uses oxygen to produce ATP.

Iron may shift to the Fe³⁺ state when exposed to artificial blue light, impairing oxygen binding and leading to mitochondrial hypoxia — meaning your mitochondria suffocate. Over time, this dysfunction can reduce your body’s ability to burn fat and contribute to fat accumulation in the liver.

In short, if you consume a high-fat diet (butter + roast beef) when your body can’t use fat for energy, you get an energy deficit: fatigue, brain fog, and stress on the system. The resulting increase in cortisol also leads to fat storage, and an inability to burn fat.

Low-fat, high-carb as a temporary fix

When inadequate sun exposure weakens your mitochondria, a low-fat, high-carb diet might provide short-term relief. To produce energy, carbs require less mitochondrial processing compared to fats. In addition, when your mitochondria are impaired, carbs preserve muscle mass. On a keto diet, the body may start breaking down muscle protein to meet its energy needs.

In the long-term, however, consuming too many carbs without proper metabolic flexibility can lead to insulin resistance, especially if you’re not active enough to burn off the glucose. Additionally, relying on carbs when mitochondrial function is poor can lead to uncontrolled blood sugar spikes and crashes. The body’s use of glucose pathways for energy, instead of fat, is associated with a variety of diseases.

The fastest route to health is always the same: Go outside at dawn — in this case, so your body can burn fat as nature intended.