November 16th, 2018

Ketogenic diet = very low carbs, moderate protein and LOTS of fat

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Do the pros of the ketogenic diet outweigh the cons? In my opinion, they don’t. Here's why…..

The ketogenic diet has gone from a pediatric therapeutic diet to a fringe fad diet to a mainstream fad diet! I frequently get questions about what this diet is, whether it’s effective for weight loss, and whether it’s safe.

I’m sure you’ve already heard all sorts of opinions on the pros and cons of “going keto” from celebrities on social media to people in your office or gym, based on their personal experience or stuff they’ve read on the internet. Here is a science-based perspective on the evidence we have thus far.

What's the Evidence for the Ketogenic Diet?

The evidence for the ketogenic diet for weight loss is pretty flimsy.
This diet has been very well researched as a medical-nutrition therapy to control seizures in kids with epilepsy. Although it can be very effective in preventing seizures, it is usually conducted with medical supervision (not just because epilepsy is a serious condition), but because the diet is so extreme and potentially risky for general use.

Now, it is almost a mainstream diet and weight loss trend, flogged in best-selling diet books, by celebrities and personal trainers, and other people that you might not want to take medical advice from.

What Is A Ketogenic Diet?

Since the ketogenic diet has become so popular, the meaning of the term has also become weakened. Many people say they are "eating keto" because they choose “keto” snack foods, energy bars, or eat a cauliflower crust pizza. A true ketogenic diet is extremely low in carbohydrates, usually less than 50 grams per day, or about 10% of calories. (We typically eat about 40 to 65% of our calories from carbs). Carbohydrates are found in fruits, vegetables, pulses (lentils, dried peas, beans and chickpeas), and dairy foods.

The idea is to eat so few carbs that it forces your body into a state of ketosis. Instead of using glucose from your food or glycogen from your muscle to fuel biological processes, your body will turn fat into an alternate source of energy called ketones. For those tissues and organs that can’t utilize ketones, the body also has a way of turning amino acids from protein into glucose.

One thing that people like about ketogenic diets is that, as long as you strictly restrict your carb intake, you can eat as much as you want! Ketogenic diets are moderate in protein and very high in fat, up to 80% of calories come from fat. 

Is the Ketogenic Diet Effective for Weight Loss?

You will probably lose weight on a ketogenic diet, despite being able to eat as much as you want (of a very limited number of foods). Despite to what you read online, very little of this has to do with the metabolic "magic" of ketosis. Converting fat into ketones and protein into glucose does burn a little more energy than burning carbs for fuel. But this ends up being a very small factor. The main reason that people lose weight on ketogenic diets is that they simply take in fewer calories.

Being in ketosis has a significant appetite-suppressing effect. Anything that suppresses your appetite is obviously going to make it easier to limit your calorie intake. Another reason that people take in fewer calories is that a very high fat diet—as great as that may sound—is not very appetizing.

You’ll lose weight quickly: True
Weight loss on a ketogenic diet is likely to be fairly rapid, especially at first. But much of that initial weight loss is water. Being in ketosis is very dehydrating and can even lead to electrolyte imbalance. (This is why this diet used to only be done under medical supervision.)

You'll lose more fat: False
Although a ketogenic diet does force your body to burn fat for fuel, research finds that this does not translate into losing more body fat. In studies that have compared the ketogenic diet to other diets, total weight loss and fat loss was not significantly different. In some studies, lean tissue loss was greater on ketogenic diets than on other diets. If you are on a ketogenic diet, you can mitigate some of the muscle loss with strength training

The truth is that rapid weight loss sets the stage for weight regain, by increasing lean muscle loss and decreasing your metabolic rate. That’s why I’m always promoting slow and steady weight loss!

How Does the Ketogenic Diet Affect Disease Risk?

Most of the research on ketogenic diets and its effects on diabetes or heart disease risks has been done on rats. And, for rats the ketogenic diet isn’t looking so good. It tends to increase bad cholesterol and triglycerides and reduce good cholesterol. It also increases insulin resistance and diabetes risk.

Things seem to go a bit better for humans than they do for rats. For type 2 diabetics, the ketogenic diet appears to have positive effects on blood sugar, but unfortunately, these appear to be temporary.

The ketogenic diet also tends to have positive effects on cardiovascular risk factors such as triglyceride and cholesterol levels in humans, but this may be mostly due to weight loss and not specifically the ketogenic diet. Unfortunately, we’re lacking data on the long-term effects of ketogenic diets on heart disease and diabetes risk.

Research suggests a high-fat ketogenic diet that emphasizes unsaturated fats like olive oil, nuts, and avocados and not overdoing it with saturated fats such as coconut oil and butter may offer your heart some protection and lower your diabetes risk.

Are Ketogenic Diets Sustainable?

That’s the million-dollar question! There isn’t much data on the long-term sustainability of the ketogenic diets in humans, but longer-term studies in rats aren’t promising. Rats put on a ketogenic diet tend to lose weight initially but after a few months, weight loss slows—which wouldn’t be so bad, if they stabilized at a lower weight. But instead, they start regaining and ultimately end up heavier than when they started.

We don’t know whether it might work the same in humans. The "long-term" human studies we have max out at about 6 months, which is right about the time that the rats started regaining their weight.

But the more important question is whether you can make this very restrictive diet part of your permanent lifestyle.

You have to be on a very low-carb diet for about three days in order to get your body into a state of ketosis—and a single carb-rich meal will put you back at the starting point. Without the appetite-suppressing effect of being in ketosis, continuing to eat a lot of high-fat foods could lead to taking in way too many calories.

If you get tired of the ketogenic lifestyle, you are going to need to find a new strategy for managing your appetite and your calorie intake. Otherwise you are likely to regain what you’ve lost. And do you really want to go through all that deprivation to end up where you’ve started? And, losing weight and then regaining it may be more harmful to your health than not losing weight at all.

The other thing that concerns me about long-term use of this diet is that very low-carb diets are likely to be low in fibre, folate, vitamin C, calcium, and other vitamins and minerals. If you are committed to this as a long-term adventure, be sure that you have those bases covered.

The Bottom Line

Do the pros of the ketogenic diet outweigh the cons? For me, they don’t. Whatever path you take to lose weight, needs to be a path you can stay on for the long-term. I’d rather see you lose weight more slowly, because this helps preserve your metabolism and lean muscle mass and will likely set you up with eating and lifestyle habits for the healthiest you!

Unfortunately, a lot of people are still in the market for fast weight loss by whatever means. I’m sure my verdict isn’t going to put a dent in the keto madness. But if you’ve been wondering whether you should jump on the keto bandwagon, I hope this overview of the pros and cons will be helpful in making the best decision for you!