The FatBurn Fix By Catherine Shanahan, MD

Author: Dr. Ron Hunnginhake, MD

Dr. Shanahan’s book lucidly explains why 80% of the United States’ population and most of the Western world are suffering from metabolic syndrome. Her key insight is that the ubiquitous use of industrially processed polyunsaturated vegetable oils significantly dysregulates the human mitochondria’s ability to properly metabolize fat. This key disruption accelerates aging, causes insulin resistance, and results in a rapid increase in liver dysfunction with visceral fat accumulation. All of which serve as the devious foundation for the acceleration of ALL of the major complex chronic illnesses plaguing western society, including obesity, diabetes, hypertension, heart disease, autoimmune disorders, depression, mental illness, cognitive dysfunction, and cancer.

Obesity and Dysfunctional Fatburn

The belief that all obese people have metabolic syndrome is incorrect. Around 30% to 35% of the normal weight population already have metabolic syndrome. Similarly, being overweight does not mean you automatically have metabolic syndrome. Some overweight people are metabolically normal, usually, if they are exercising, eating whole foods free of processed vegetable oils and fructose corn oil sugars. The food and beverage industry wants you to think that metabolic syndrome is simply a lack of exercise and self-restraint. However, they know that the rampant use of processed sugars and vegetable oils INCREASES the addictive nature of processed foods. Add in lower prices and convenience, and they’ve got you hooked!

Bad Fat Facts

Dr. Shanahan’s book reveals that over the last 20 to 25 years, since the ’70s and ’80s when all saturated fats were demonized, there’s been a solid effort to substitute saturated animal-based fats with polyunsaturated vegetable-based oils. Of course, all the nutrition authorities said, “Hey, great! Plant-based fats, this is exactly what we need.”

But the problem is that most of these oils come from seeds that have been put in ultra-high pressure presses that squeeze every last bit of oil out but at the cost of changing perfectly healthy oils into the dreaded trans fats! The big six offenders are soybean oil, canola oil, corn oil, safflower, sunflower, and cottonseed oil.

These oils are being used ubiquitously in packaged, processed foods because they are cheaper than more stable oils. But unfortunately, polyunsaturated fats are biochemically loaded with double bonds that are exquisitely vulnerable to oxidation. When they oxidize, they form hydrogenated fats, which have been shown to have significant adverse health issues. These oxidized oils go rancid and must be chemically camouflaged not to taste bad. About 70% to 80% of processed foods contain these health eroding oils. Yet, almost all packaged foods, fast foods, convenience foods, and restaurant foods use these oils because they are cheaper and generally undetectable by the average human palate. Hence, these “Frankenstein oils” single-handedly constitute a slow-motion global nutrition disaster!

Mitochondrial Dysfunction!

Dr. Shanahan points out that our mitochondria, the cellular organelle that burns fat, cannot efficiently burn these types of fats. Their metabolic efficiency drops by a whopping 80%. This is why metabolic syndrome is characterized primarily by the symptom of chronic fatigue. These fats make you tired. Ironically, the best fats are saturated fats. Dr. Shanahan quotes a study done out of Italy where they measured the metabolic functioning of the mitochondria. They found that in addition to these fats, oxidized vegetable oil functions at a low 20% whereas saturated fats function at a normal 100%. The surprising part of that story was that monounsaturated fats improved energy production by another 20%. So you were getting a 120% utilization of energy in your mitochondria from the monounsaturated fats, such as coconut oil, avocado oil, and extra virgin olive oil. These monounsaturated fats are the fat-burn superstars. They also do not oxidize in storage and are resistant to oxygenation. You have to be careful when you go out to eat because you don’t know what oils the restaurants are using. More often than not, they are going to use the cheapest oils. Unfortunately, you can’t taste these oils, and they don’t taste rancid. Cheap, unhealthy, and very sneaky!


  1. Eat natural fats, not vegetable oils.
  2. Eat slow-digesting carbs, not starchy carbs or sweets.
  3. Seek salt.
  4. Drink plenty of water.
  5. Supplement with vitamins and minerals.

Her revolutionary, step-by-step fat-burn plan is easy to follow and can be implemented in as little as two weeks. In summary, with The Fatburn Fix, Dr. Shanahan shows how regaining your fat-burn potential is the key to long-term weight loss and a better quality of life, with abundant energy and long-term health and happiness.



  1. Shanahan, D., Catherine. The Fatburn Fix: Boost Energy, End Hunger, and Lose Weight by Using Body Fat for Fuel. Flatiron Books, 2021.