Why We Use a Ketogenic or LC/HF Diet For Weight Loss
The ketogenic diet has hit the mainstream. Google announced that it was the most searched for health term in 2018, and the word “keto” provokes passionate debate over if the diet is unilaterally “good” or “bad” for you. Few articles examine why the diet may be appropriate (and almost mandatory) for some and not as valuable for others.
For our purposes, I will use the LC/HF (low-carb/high-fat) and ketogenic diet terms interchangeably. The common core is a dietary strategy that uses fat as the predominant energy source. That’s it. There is nothing THAT controversial or new about a diet that is low in sugar (the body quickly turns carbohydrates into glucose/sugar, some faster than others).
We often use a LC/HF diet with our weight loss clients, because it is incredible for significant weight loss. Someone who needs to lose a few pounds may see moderate results and will discover some great ancillary benefits, but the diet is really amazing with the obese. People that are significantly overweight almost always suffer from a high level of insulin resistance. Because of overuse, the systems in the body that process glucose no longer work well, leading to blood sugar issues and fat storage. Carbohydrates spike blood sugar significantly, protein causes a moderate spike, and fat does not affect blood sugar at all.
We accept that significant calorie restriction is not sustainable and does more harm than good, so the loss in calories needs to be substituted by either fat or protein. Because of its non-effect on blood sugar, we use fat as the principle replacement energy source.
Without getting too deep on the science, the body first uses glucose for fuel because it is typically plentiful and easily converted to energy. When it runs out, it uses fat. If the body never gets low on sugar, fat stores sit idle. A healthy person should be able to switch energy sources easily depending on what is available. Many people will have to re-teach their body how to use fat as a fuel source, but that’s a critique of our standard diet and habits, not an argument for carbohydrates.
While sugar is available to the body, significant fat loss won’t happen. The solution is to get rid of the sugar. Intermittent fasting will use up extra sugar in the body, and so will exercise. But the easiest way to fix the problem is to not have the extra sugar there in the first place. Unlike fat or protein, the body does not actually need any carbohydrates at all. The small amount of glucose our internal systems require can be made in the liver, so for the purpose of using fat for energy, carbohydrate intake should be kept as low as is reasonable.
There are additional benefits (decreased inflammation, improved brain health, mood stability, etc.), but the principle reason that we suggest a LC/HF diet is that it allows body fat to be used for energy. That’s it. Carbs aren’t evil. Sugar isn’t evil. We use a LC/HF diet as a tool for people with a broken energy system because it works and is backed up by research and experience. If you are not insulin resistant, nor headed that direction, a diet like this may not be as beneficial. Simply eating whole foods, removing added sugars, and narrowing the daily feeding window may be enough for someone who is not yet dealing with insulin or blood sugar issues.
An argument against a ketogenic diet typically centers around nutrients, and a concern that low-carbohydrate consumption will lead to poor nutrition. Many carbohydrate sources (grains, boxed items, etc.) have vitamins added in at the end to replace what has been removed during the processing stages, and for someone with a poor diet, these nutrients may be valuable. But eating a properly constructed LC/HF diet will provide the body with every micro-nutrient it needs. Even the touted vitamin troves in fruit are easily found elsewhere in vegetables and meat. The fear of high fat diets is largely based on old, incorrect science; properly constructed high fat diets have been shown to improve heart and general health.
As a final note, always do your own research. Jillian Michaels recently criticized the whole “keto” movement with the standard arguments mentioned above (her lack of scientific understanding makes me uncomfortable, as I’m sure she has a ton of people who will just assume she knows what she is talking about), and preached calorie restriction, “healthy eating”, and exercise. This is all fine of course, if vague. But we want to use something that is concrete, effective, and sustainable. Let’s look at one of Michaels’ The Biggest Loser seasons. Caloric restriction, “healthy eating”, and exercise led to weight loss. It was unsustainable and ultimately resulted in weight gain and a destroyed metabolism.
This is an extreme example, but it is representative of standard weight loss attempts.
We use a ketogenic diet as a tool to help our overweight clients fix their bodies. Many of them continue using the diet after they reach their weight loss goals, but often carbohydrates can be added back in once the body is working like it was intended. At that point, the energy source can be easily switched back and forth between glucose and fat. The ketogenic diet isn't magical, shouldn't really even be controversial, and requires changes and commitment just like any other lifestyle reform. That said, we have found it to be life-changing among many of our clients looking for significant weight loss.