The keto diet is still everywhere.
This diet was developed to treat epilepsy in children, and is still used successfully for that purpose. But it has been co-opted by biohackers and people who want to lose weight.
In short, the idea of eating a ‘ketogenic diet’ is to induce ketosis, which is a state our bodies enter when we run out of glucose (most readily supplied by carbohydrates in our diet) to supply our energy needs. In that situation, our bodies switch to using stored fat, which gets turned into ketone bodies through a process called ketogenesis. These ketone bodies are used as energy by the body.
Although we can survive on a ketogenic diet, our bodies’ first line substrate for energy is glucose, which is produced when we eat carbs.
In the absence of carbs in the diet, a small amount of glucose can be made by the body from protein and fat, in a process called gluconeogenesis. Gluconeogenesis is an inefficient process, however, and doesn’t yield the amount of glucose that we’d have on a diet that contains even moderate carbs.
The whole ‘burning fat for energy’ thing is what attracts a lot of people to the keto diet for weight loss. And while keto has been shown to help some people lose weight and manage glucose levels better, let’s get the tough part on the table right away: this way of eating does have substantial challenges.
First off, it’s restrictive. Getting yourself into ketosis requires eating a whole lot of fat – usually 70-80% of your calories, a moderate amount of protein, and a very low amount of carbs – usually under 5%
Remaining in ketosis is no easy feat and requires constant monitoring. Many adults on a keto diet are probably not even in actual ketosis. That’s because getting into ketosis not only requires a higher-fat diet; if you eat too much protein, it will be broken down to glucose.
That’s why you’ll hear a lot of keto dieters talk about being ‘kicked out’ of ketosis by eating too much protein. How to get more fat to the keto diet is a legit search result on Google that’s getting a lot of hits, for the simple reason that it’s hard to meet the fat macro for keto.
A diet that’s almost all fat isn’t easy to eat, tolerate, or stick to. There are plenty of healthy foods that are allowed on keto, including nuts, avocado, lean meats, fish, olives, and some dairy. That being said, there’s plenty of ultra-processed foods that are labelled ‘keto.’
Most fruits, normal (aka not keto) bread and pasta, starchy vegetables, beans and lentils, and a whole lot of other foods are off limits. A life without these things isn’t exactly most peoples’ idea of fun. Sure, you can eat these foods on keto, but the diet isn’t meant to be rotational in nature: there’s no ‘sort-of’ ketosis. You’re either in it, or you aren’t.
Any weight loss that’s associated with the diet depends on you sticking with it forever. The need to stick to the diet religiously (to avoid falling out of ketosis with a switch back to glucose metabolism) is very hard to do.
It’s a popular opinion that many people on the keto diet aren’t actually in ketosis at all: they’re eating too much protein or carbs to actually be in that state.
Keto can also be expensive. Specially-made keto breads and other products are costly. A lot of keto communities recommend grass-fed meat, fish, and butter, which are a lot more expensive than their conventional counterparts. There’s no resorting to rice, beans, and lentils for a cheaper meal.
Eating no carbs can affect your workouts and your overall energy levels. Some people function fine on keto, others find that the lack of glycogen leaves them with zero energy. There’s also the dreaded ‘Keto flu’, the miserable feeling of fatigue, nausea, and abdominal pain that some experience.
The diet can be socially isolating. If you’re not eating carbs, it can be tough to eat anywhere but at your home. Sure, there are keto options at most restaurants, but when your friends are eating pizza and pasta, do you want to be the one eating a salad?
Some people are fine with that, but it’s just another point to consider.
As far as ketone supplements that claim to put you into ketosis without the keto diet, don’t bother. Nutritional ketosis takes work, and supplements won’t do that work for you.
(I reviewed Pruvit exogenous ketones here)
Does keto increase cholesterol levels?
A low fat keto diet doesn’t really exist. And while it’s possible to consume mostly unsaturated fats while doing keto, I’m betting that most people who are on this diet don’t do that. One point of contention around keto has always been its potential effect on cholesterol levels.
Our blood cholesterol levels are complicated: there are subtypes of both LDL and HDL, and they vary based on many things including *genetics*, weight, physical activity, diet, smoking, alcohol, and underlying organ function. Cholesterol is made in our liver, and excreted into the blood, where it can be measured with routine blood tests.
(Ray Peat carrot salad: can it fix your hormones?)
To further complicate things, there is a concept of ‘dietary cholesterol’ which is different from blood cholesterol. We used to believe that dietary cholesterol directly affected our blood cholesterol levels, but we now understand that this isn’t the case for most healthy individuals. This has resulted in a lot of dietary recommendation flip-flopping, which has been a source of frustration with a lot of people.
While research doesn’t fully establish causation, diets high in saturated or trans fats, in particular from meats, have been shown to increase cholesterol levels. The high saturated fat content and lower fibre content in many keto diets has been observed to increase LDL.
If you’re doing a keto diet, I highly recommend you consume the majority of your fats as unsaturated ones.
Is the keto diet good for diabetics?
You don’t have to look too hard to find people who claim that they’ve reversed their diabetes with the keto diet.
Unfortunately, diabetes isn’t something that can be cured. Type 2 diabetes can be put into remission, and this mainly occurs with weight loss. This is because excess weight causes insulin resistance, leading to higher blood glucose.
The term ‘reversal’ is often used interchangeably with ‘remission,’ but I think ‘remission’ is more accurate, given that people who have had diabetes will always be at a greater risk for high blood sugars.
The DiRECT trial out of the UK showed that remission is associated – and dependant on – weight loss. The problem with that trial is that participants were put on an 800-calorie diet for 3-5 months before transitioning into a diet that was 50% carbs, 35% fat, and 15% protein (aka NOT keto).
There’s a large variation in the definition of the term ‘remission’ where diabetes is concerned, which is a stumbling block for the research around this topic. The NIDDK defines remission as normal blood sugars, without any glucose-lowering medications, for 6 months or more.
Type 1 diabetes can not be put into remission or cured, either – except with a pancreatic transplant.
The keto diet most definitely can help with lowering blood sugar, but these effects can also be seen with a lower-carb diet that’s not ketogenic. In this case, quality of carbs may be just as or more important, than quantity. With a low carb vs keto diet, the difference obviously is more carbs, which can make a huge impact on quality of life and sustainability. I recommend a moderate carb diet for most people.
Just because someone eats a moderate or high-carb diet, doesn’t mean that this person has an increased risk for diabetes. There are many other factors at stake, including diet quality, genetics, and lifestyle.
The keto diet plan for weight loss.
A lot of people jump on the keto diet to lose weight fast. And yes, the keto diet can lead to weight loss. But as I mentioned above, it’s tough to stick to, and can be limited in food variety.
That being said, some people don’t care about those things, and are fine eating a keto diet for the rest of their lives.
It’s important to note that the research shows that the keto diet is no better than any other diet (and here) for weight loss. Initial loss may be greater, but over the long-term, is not.
Want to lose weight? Here are three checks to do first.
Weight loss is always the result of a caloric deficit – there’s really no way around that: just because you’re using fat as fuel when you’re in ketosis doesn’t mean that keto gets around the laws of thermodynamics. The best diet is the one you can stick to. If that’s keto, and it works for you and you can sustain it for the long-term, that’s great…for you.
Does keto boost metabolism?
No diet boosts metabolism. If you lose weight on keto, it’s because you’re in a caloric deficit. In fact, fat has the lowest thermic effect of food of any of the macronutrients.
Metabolism boosting claims are always a red flag.
Do metabolism-boosting foods and supplements exist? Here’s the real story.
How does keto impact gut health?
The keto diet is somewhat notorious for being low in fibre. While green vegetables are allowed on the diet, most fruit and all grains aren’t – and these foods tend to be some of the main sources of fibre in our diets.
It goes without saying, that anyone who says that we don’t need fibre, or vegetables and fruit, is having a serious lapse in judgement.
Some keto warriors claim that fibre is useless, which is completely false. Fibre is filling, it may reduce cholesterol levels, and it’s what feeds our good gut bacteria. On the other hand, the saturated fats in keto may have a negative impact on our gut health. As a dietitian the one-two punch of a diet high in sat fats and low in fibre isn’t anything I would recommend.
Studies suggest that diets high in fat, and high in saturated fat, appear to negatively impact good gut bacteria. Whether this in turn has a negative impact on health for the majority of individuals, remains to be seen.
A recent review of the research suggests that the ketogenic diet may impact gut health, but the results are mixed, and studies are mostly methodologically weak.
My review of the Beachbody 4-Week Gut Health Protocol.
Does keto decrease appetite?
Here’s the thing: keto involves eating quite a bit of fat, which is really filling. And while there are a lot of ultra-processed keto snack foods, the basis of the keto diet should be whole foods, which are also satiating.
It’s thought that ketosis may also blunt appetite by suppressing the appetite hormone ghrelin and increasing satiety peptides, although more research is needed.
In any health outcome, there’s always the question of if these were the result of the keto diet, versus weight loss that resulted from it.
A dietitian’s recommendations: is keto safe in the long-term?
We don’t really know, to be honest. What I can say is that if you do choose to do a keto diet, make sure you’re ready to stay on it for the long term. Also understand that you don’t need to take things that far – even taking your carbs down a notch may have a positive impact on several factors, depending on your situation.
Co-written by Lise Wolinyuk