Could A High Fat Diet Be The Key To Longevity?

Oct 4, 2017

Jon Ramsey with the UC Davis School of Veterinary Medicine holds a mouse. His study found that a high fat diet makes mice live longer.
Credit Don Preisler/UC Davis photo

New research points to a high fat, low carbohydrate diet increasing longevity and improving muscle coordination and brain function in aging mice.  Will this new way of thinking about diet and aging buck the trend of the “traditional low-fat diet?”  

According to a 2016 study from the Federal Interagency Forum on Aging Related Statistics, Americans are living longer than ever before.  Those who get to 65 can expect to live an average of 19.3 more years.  As longevity increases, studies on how to age well are abundant.  Dr. Jon Ramsey, a professor in the department of Molecular Biosciences at the University of California Davis’ School of Veterinary Medicine has worked for two decades researching the factors that lead to aging in both humans and animals. 

“We’ve been interested in calorie restriction for many years.  And calorie restriction has sort of been the gold standard that’s been used by investigators studying aging because until recently it’s really been the only intervention that’s consistently been shown to increase lifespan in a wide range of animals.”

It goes against conventional wisdom that a diet rich in fat would lead to increased longevity.  But that’s exactly what Dr. Ramsey and a team of researchers found in a recent study. He wanted to learn how a ketogenic diet, low in carbohydrates and high in fat, would impact the aging process. 

“So what we wanted to do was design a diet where we would force the animals to go into relying on fatty acids or ketones as an energy source.  (We) wanted to feed them a diet where they ate their diet and maintained their middle age body weight.”

Dr. Ramsey says the very strict keto diet has been used for decades to treat epilepsy.  Here’s the science of keto:  Fat is the main source of calories in the diet, making up about 65%.  About 35% of calories comes from protein.  Very little calories come from carbohydrates.  That’s because when there’s not enough glucose for energy, the body will switch over to burning stored fat.   Ketones, which are a byproduct of stored fat being broken down for energy, are used as an alternate fuel in a metabolic process known as ketosis.

For the study, a group of middle aged mice were fed a regular rodent diet rich in carbohydrates.  Another group received a low carb/high fat diet.  And the last group, (the most extreme diet) a no carb ketogenic diet in which the mice achieved ketosis.  Rather than focus on weight loss, Dr. Ramsey observed how the diet affected metabolism and was surprised by the results. 

“So we didn’t see decreases and deficits in memory, we saw improved muscle coordination, muscle strength in later life.  And so in the old animals, really almost any functional measurement that we looked at, the mice were doing better than the control animals and weren’t really showing age related deficit and function.”

Humans and mice have many genetic, anatomic, and physiologic features in common.  Mice studies have informed medical breakthroughs for more than a century.   The new study found mice on the ketogenic diet had a 13% increase in median lifespan.  On a human scale, this would be an increase of seven to 10 years. 

As promising as these results sound, Associate professor with the Department of Nutrition Science at East Carolina University's College of Allied Health Services Dr. Roman Pawlak is unconvinced.

“I do not know whether there is any application in terms of the finding in this study to us as humans.”

Dr. Pawlak says he has a number of concerns with the study.  First, the diet fed to the subjects hardly resembled foods we as humans commonly eat. 

“So for example, those in a high carbohydrate diet receive corn starch, glucose, surcrose, soybean oil and lard.  Okay?  Those on the ketogenic diet receive soybean oil and lard.   So how would this be applicable to humans?  How many people can anyone know that would want to consume a diet that is composed of soybean oil and lard?”

There are some pitfalls with the keto diet, most notably the effects of a lack of fiber.  And “keto flu” as the body transitions to getting energy from ketones.  Symptoms include fatigue, dizziness, headaches, difficulty focusing, and nausea and can lasts a day or a few weeks.  Dr. Pawlak believes a less restrictive, well-rounded diet with no adverse effects is the key to longevity.

“And when we look at the longevity cultures and populations, blue zones so called, such as Okinawans in Japan and Seven Day Adventist which are all over the world including in the United States, they eat high carbohydrate diets that are relatively low in fat.  But again, these diets aren’t composed of refined glucose, sucrose, and corn starch.  These carbohydrates come from fruits, unrefined grains mainly, veggies and legumes.”

Whether it’s for longevity or weight loss, ketogenic diets are somewhat controversial.  Some call it dangerous because it requires entire food groups to be cut out.  Others say keto makes bold claims that can’t be backed by enough research.  In the process of researching this report, I reached out to more than a dozen dieticians and nutritionists in eastern North Carolina for their thoughts and questions about this study.  Most declined.

“With my studies, I think you have to view those as a study that gives you information potentially about mechanism and proof of principle.” 

Even one of the authors of the study UC Davis’ Dr. Jon Ramsey admits further research needs to be done.  He says the conditions needed to convert a portion of body fat into ketones requires an extreme diet to produce that kind of change in metabolism and adds it’s not a practical diet for most people.

“And I think our goal now is to try to say if it is something about ketones that’s important for aging, I think the next step is to try to design less restrictive strategies that might have the potential to be tested and used in humans.”

The findings of this study didn’t surprise New Bern resident Ben Knight. Even though he says he generally eats a clean, healthy diet, he says he feels better on keto.

“I was losing a lot of body fat.  I had really good results with it. I really enjoyed being able to indulge in fatty foods that you don’t normally get when you’re on a clean diet.”

The 42 year young former football player and mixed martial arts fighter did his first keto diet three years ago.  Knight has completed a half a dozen keto diets lasting about 12 weeks at a time.  When I asked him if he would go on keto full time to reap the benefits of longevity, he said it’s something to consider.

“As I get older, and I see myself faltering a little bit in health, I would probably do this a little more.  Because when I’m on a ketogenic diet, inflammation is down, everything is down, it works better for me.” 

In September, a companion study was published by the Buck Institute for Research on Aging showing that a ketogenic diet extends longevity and improves memory in aging mice.