• He says the sugar-free eating plan has helped him slim down even though he eats a lot of fat.
  • Harper has written a new book, " Biodiet ," about how to follow the trendy keto diet in a healthy, science-backed way.
  • One of the problems with modern "Western" diets, he says, is that they tend to promote inflammation, obesity, and disease by relying too much on sugar and other carbohydrates.
  • Visit Business Insider's homepage for more stories .

Start the day off with a piece of toast, a bit of margarine and jam, and a glass of fresh orange juice ? Definitely not, says cancer researcher David Harper.

The kinesiology professor hasn't eaten toast in more than six years: He started following a high-fat, low-carb ketogenic diet strategy in 2013, and said he's never looked back.

Harper said he and his wife, Dale Drewery, both rely on fat to power them through the day.

"I eat full-fat cream in everything," Harper told Business Insider, adding that he consumes lots of nuts and seeds, green beans, "organ meats" like liver, and up to a dozen eggs each week.


Harper and Drewery have written a new how-to book about going keto, called " Biodiet ," which was released in May. In it, the couple suggest that our modern diets are formulated around too much sugar and too few veggies .





The 'axis of illness' on our plates

david harper and dale drewery
david harper and dale drewery
Biodiet authors David Harper & Dale Drewery

On a well formulated keto diet, the idea is that no more than 5% of a person's daily calories come from carbs, while around 80% is made up of fat. Harper said he and Drewery will often split a fat-marbled steak for dinner, or pair a bit of chicken (fatty skin left on) with low-carb shirataki noodles made from Japanese yams.

Harper thinks that cutting carbs in this way will help him and Drewery both live to a ripe old age and stay sharp, trim, and satiated.

"We're not eating a lot of packaged foods, we're not eating a lot of processed foods," he said.

Harper also avoids pasta, potatoes, and sandwiches, along with some naturally carb-heavy items like beans and apples. The latter part of that approach can be controversial, since many studies suggest that people who eat more fiber a carbohydrate present in many vegetables, whole grains, and pulses tend to live some of the longest lives .

Harper said he gets his daily fiber from veggies like cauliflower, peppers, and salad greens "anything that grows above the ground that's not a grain or a fruit or a bean, other than green beans," as he put it.




Eating fat does not necessarily make you fat

carrots and hummus snack healthy
carrots and hummus snack healthy

For a long time, the conventional wisdom was that if you restrict calories no matter whether they be from fat, carbs, or protein then avoiding weight gain should be a cinch. Cut down on dense, 9-calorie-per-gram fats; fuel up on 4-calorie-per-gram carbs and a little protein instead; get some exercise; and voila: a winning low-fat lifestyle.

But, "we've tried that for 40 years, and it's not working," Harper said.



Recent research even showed that sweet, all-natural juice can be almost as bad for our livers and blood-sugar levels as soda, and may contribute to disease and early death in a similar way.

Unfortunately, the public-health push to eat "low-fat" which was especially popular the 80s and 90s led some people to replace fatty foods like bacon and butter with low-fat alternatives that were often loaded with sugar to maintain taste. That now seems to have been a misguided and often lobbyist-driven diet agenda that caused people to gain weight .

"That is unfortunately a myth, that eating fat makes you fat. But it's a myth because it makes sense," Harper said. "Fat calories are twice as dense."

Keto or not, we should all probably eat more veggies

Today, more than one in three Americans battles diabetes or pre-diabetes, and the numbers are rising . A 2017 Harvard study suggested that 57% of US kids will be obese by the time they're 35.


"Keto is undeniably the best way to deal with Type-2 diabetes and insulin resistance," cardiologist Ethan Weiss, who follows a keto diet plan himself, recently told Business Insider .

Obese woman
Obese woman
Marjan Lazarevski



However, nutritionists and doctors generally agree that nobody's system should run on sugar alone. Adding more fresh veggies to your plate is almost always a beneficial change, as is lowering your intake of ultra-processed snacks.


NOW WATCH: 5 myths about sugar that you should stop believing

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SEE ALSO: A cancer researcher who's been on the keto diet for 6 years explains how he does it