The ketogenic diet.

Read this before trying.

The ketogenic diet is not new.  It’s been around in official form since the early 20th century, when it was an accepted treatment for epilepsy and seizures, before anticonvulsant drugs were developed.  But people have known for centuries that diet restriction could help control  seizures.  In Ancient Greece, epilepsy was blamed on supernatural intervention, but some physicians discovered that fasting stopped the seizures.  Since fasting for prolonged periods isn’t really a great solution, variations on diet restrictions were used over time.  Eventually the standard very high fat ketogenic diet was developed.  Being in the ketotic metabolic state does suppress seizures, but even now, 100 years later, we don’t understand why it works.

One well known side effect from using a ketogenic diet for seizure treatment is that it leads to weight loss.  Back before the obesity epidemic, weight loss was not a desirable outcome, especially for children.  Children need to grow and gain weight.  Today, some children with seizure disorders are still treated with a ketogenic diet, and the parents must work closely with a registered dietitian and physician to make sure the child eats enough calories and protein, and is supplemented with necessary vitamins and minerals for healthy growth.  Given the nature of the diet, it’s very difficult to do.

Over the past few decades, the ketogenic diet has been popular off and on as a weight loss strategy.  Recently it’s back in the public eye, even though it obviously didn’t prevent the obesity problem when it was in vogue in the 1970’s.  If you’re considering this diet, there are some important things you need to know.

What happens when you eat this diet?

Ketosis is a metabolic condition resulting from starvation, or insufficient energy supplies.  When cells have insufficient supplies of the preferred fuel, glucose, fat is the back-up energy source.  Fat tissue or fat from food is burned instead.  A by product of fat metabolism are ketone bodies, which are acids.  If enough fat is burned for a prolonged period of time, ketones build up in the system and spill into urine.  Ketoacidosis occurs when ketones build up to toxic levels in blood.  People with Type 1 diabetes are at risk for this.  Without insulin to push glucose into cells, the body is forced to metabolize fat. In severe situations, ketoacidosis can lead to coma.

People using the ketogenic diet for weight loss maintain a ketotic state by severely restricting carbohydrate foods, relying instead of high fat foods.  With very few carbs to burn for energy, cells begin metabolizing fat, from diet and, if calorie intake is restricted, from fat tissue.  The diet is typically about 75% calories from fat, 20% protein and just a mere 5% carbohydrate (normally a typical diet would be more like 30-35% fat, 15-20% protein and 45-65% carbohydrate).  That means high carb foods like bread, cereals, pasta, rice, legumes, corn, tortillas, fruit, juices, potatoes, all bakery items, chips, frozen desserts, milk, yogurt, candy and the like are off limits.  Very small amounts of certain low carbohydrate vegetables could be used in small portions.

This is not a high protein diet, by the way.  Protein is eaten in more normal amounts, not large amounts as with some other weight loss plans.  The point of the ketogenic diet is to eat lots of fats, so your body is (theoretically) forced to burn more fat.

How much fat can you stand?

When children go on a ketogenic diet for seizures, sufficient food intake is a problem precisely because of the high fat requirement.  After a short while, all that heavy fatty food gets old quickly.  If you’re starting this regimen for weight loss, unlimited cream, butter, oil, bacon, peanut butter, avocado and eggs might sound good at first.  But when that’s pretty much all you get, and you have to eat those every day week after week, it can become monotonous.  You can have a cheese burger, but no bun or potatoes or condiments.  You can have cream, but it can’t be sweetened.  And because you’re avoiding so many nutritious foods, you can easily develop nutritional problems.  Calcium intake is drastically reduced, for example.  Potassium and magnesium will also be low.  Fiber is almost non-existent, so your digestive system is impacted.  Vitamins A and C and B-vitamins will be in short supply.

Here’s a general list of the permitted foods.  Nothing else is permitted.

  • sour cream
  • cream cheese
  • full fat cheeses
  • heavy cream
  • butter
  • eggs
  • chicken/turkey, preferably dark meat that’s higher fat
  • high fat beef and pork
  • high fat fish like salmon or sardines
  • bacon
  • vegetable oils
  • avocado
  • peanut butter and peanuts
  • other high fat nuts
  • small amounts of high water/low carb vegetables like greens, broccoli, cabbage, mushrooms, cucumbers, peppers, celery, fresh tomato, zucchini
  • water

Let’s do some fun math.  If you were following a 1500 calorie ketogenic diet, you would be limited to 75 calories of carbs a day, or the carbs in 2 TB natural peanut butter, 1 cup boiled spinach and 1/2 avocado.  That would be it for carbs for a day.  The rest of your food is limited to fats and about 9-10 oz of high protein food like meat, fish, egg or cheese (or 3 oz/meal, not much).

Because of the very high fat nature of the diet, not to mention the monotonous food regimen, many people end up eating fewer calories on this diet.  So if you lose weight, is it the ketogenic diet or is it the lower calorie intake?  That’s not clear, although for people losing weight, it’s probably not important.  If a very high fat/low carb regimen gives results and is easy to follow, that might be enough explanation.

And what happens when you go off the diet, as you eventually will, because it’s boring.  Your metabolism will revert back to normal eventually, depending on what foods you add back and how much.  Once you start eating carbohydrates in normal amounts, your body will replenish your glycogen stores, meaning you will seem to put on weight, because glycogen is stored with some water.  If you go back to your old habits, you will regain weight.

Take Away Message

If you want to try this diet, you really should consult with a registered dietitian familiar with the regimen.

  1. The diet has many nutritional consequences, from constipation to thinning bones to nutritional deficiencies.
  2. This is not a long term diet.  Ketosis is not a healthy metabolic state.
  3. Another problem: you might start smelling like acetone, or nail polish remover, because ketones are related to acetone, and when your body has high levels, you may be exhaling them when you breathe.
  4. It’s really boring.  Did I already say that?  That alone would be the clincher for me.  But for some people, a restrictive diet that eliminates all their food choices is helpful, at least in the short term.  I would never recommend anyone do this other than short term.
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