Have you heard the term “keto” lately? You may have a friend or relative who is trying out the “keto diet”, or maybe you’ve read about it on the Internet. The usual celebrities have vouched for it, including Gwyneth Paltrow (who apparently both follows and markets every diet imaginable), Kim Kardashian, and even Mick Jagger.
But what is a keto diet? And does it have benefits?
Let’s start with what it is. “Keto” is short for ketogenic. In a conventional diet, glucose – derived from carbohydrates – is the main source of fuel for the body’s cells. It’s the body’s preferred source of energy and the most efficient to use. When the body is deprived of glucose, however, it’s forced to use an alternative fuel source. In the absence of glucose the body breaks down fatty acids into ketones, which can then be used for energy. Ketogenic basically means “to create ketones”.
In order to convert the body’s fuel from glucose to ketones, a very low-carbohydrate diet is required. How low? Well, a conventional diet is usually around 50% carbohydrate, 30% fat, 20% protein in terms of calories. A ketogenic diet requires <5% carbohydrate, 75-80% fat, and 15-20% protein.
What does it mean to get less than 5% of your calories from carbohydrates? Let’s say someone eats around 1800 calories per day. 5% of 1800 is 90 calories from carbohydrates, which is only 20-25 grams of carbohydrate for the entire day. This basically eliminates all grains, sugar, fruits, and starchy vegetables – as well as most dairy – from the diet, only leaving room for a few non-starchy vegetables and the handful of carbohydrates you get from keto-friendly foods like avocados and nuts.
Protein has to be moderated as well. A keto diet is not necessarily a high-protein diet. This is because if protein intake exceeds around 20% of total energy intake, the body may start converting protein to glucose as a fuel source rather than using ketones.
Here’s an example of what a ketogenic diet might look like for someone eating around 1800 calories per day:
Breakfast – Three eggs cooked in butter, three slices bacon
Morning snack – Handful of almonds (about 12)
Lunch – Spinach salad with grilled chicken, ½ avocado, and ranch dressing
Afternoon snack – String cheese
Dinner – Five ounce salmon filet cooked in olive oil, roasted cauliflower, ½ cup full-fat cottage cheese
The above day is actually pushing the upper limit for protein (about 21%) and carbohydrates (5%). So, this is definitely a strict diet. What are people hoping to get out of it?
Let’s start with what’s proven. A ketogenic diet has been shown to be beneficial for individuals with epilepsy for reducing frequency of seizures, especially in children.
There is some discussion and research that a ketogenic diet may help fight against tumor growth, but to what extent (and in which cases) remains unclear. A ketogenic diet may improve outcomes and blood sugar control in diabetes, but then again so does adherence to a carbohydrate-controlled diet. Research on the ketogenic diet’s effects on neurodegenerative diseases like Alzheimer’s remains in its infancy.
As for weight loss, it can be helpful in some cases – but not for the reasons often advertised. Ketogenic diets are often marketed as being superior to other diets for fat loss, because “if you’re using fat for energy, you should automatically be losing body fat, right?”
Not exactly. A ketogenic diet that benefits weight loss ultimately relies on the same mechanism as any other weight-loss approach: you need to burn more energy than you take in on a consistent basis. If your body burns 2,000 calories per day, you won’t lose weight on a 2,500 calorie ketogenic diet plan. The math doesn’t change, and you can’t eat as much butter as you want and expect to lose weight.
That being said, for people who eat more carbohydrates than they need, reducing carbohydrates can be an effective strategy to lose weight. A ketogenic diet can provide a framework for (drastically) reducing carbohydrate intake, which reduces energy intake, which can lead to weight loss. There is some evidence that ketogenic diets also reduce hunger, making it easier to control portions.
As with many diets, however, the biggest problem is sustainability. How many people can eat like this long-term? No desserts, no grains, no fruit, no milk. No pizza, no pasta, no rice, no pie, no cake, no tacos (!), no potatoes. Some people can do this for a week, maybe even a month, but a week or a month of weight loss will do nothing to improve health if old behaviors come back and so does the weight. For most people, it’s not a permanent weight-loss solution.
For those brave few who do view this as a sustainable way to eat long-term, there are some additional side effects to consider. Elimination of fruit and many vegetables places a premium on meeting micronutrient (vitamin and mineral) needs. Most of us don’t get enough of these foods, and a ketogenic diet can make that even more difficult. Other common problems include constipation, elevated blood lipids, and significantly increased risk of kidney stones (no thank you).
Is the keto diet right for you? It’s not likely. Between the difficulty in following the diet and the potential side effects, it’s not worth the time and effort for the average person. It certainly would not be this dietitian’s first choice for weight loss or general health.