As a primary care physician, I get asked at least twice each week what I think about the ketogenic diet — does it really work? The short answer is yes, it works for some. The long answer is more complicated.
Keep in mind, if you have any medical problems, especially chronic kidney disease, diabetes, high cholesterol or heart disease, you should first discuss major dietary changes with your primary care physician.
What is the keto diet?
In a nutshell, the keto diet is a way of teaching your body to use fat for energy rather than glucose, or sugar. The diet focuses on limiting carbs, or foods high in flour and sugar, and increasing fat intake and proteins.
Why the keto diet can work
First, we have to think about why we eat. Our cells need glucose to work. When you experience hunger, your brain is signaling that your cells need energy. The easiest form of energy for your body to convert is glucose. So, if you eat carbs as a result of that hunger cue, your cells get the sugar they are requesting. But, if you don’t provide your body easy access to glucose, it has to work harder for its energy. It finds fat from your liver and uses the stored fats for energy. This results in weight loss.
What you need to know about keto dieting
It’s important to be mindful of your fats. Some keto diet websites and recipes will tell you to eat as much fat and protein as you want and avoid all carbs. This is very hard on your kidneys and bad for your cholesterol. My keto diet recommendation is to focus on proteins and good fats like avocado, olive oil and nuts. And don’t give yourself a pass to eat an unlimited supply of bacon.
Second, don’t avoid all carbs. You should avoid the starchy carbs and highly refined carbs, but keep your vegetables.
Starchy carbs include bread, pasta, potatoes, tortillas and rice. If you eat things from these groups, choose the brown version instead of the white. Refined carbs are foods like cookies and sugary drinks. Many highly processed or refined carbs will have high fructose corn syrup listed as an ingredient — be sure to avoid these.
Potential problems with the keto diet
I have had several patients come in for routine visits with significant weight loss using keto dieting but an elevated LDL cholesterol (the bad kind) and worsening kidney function. Like any other way of eating, anything in excess can lead to problems. Excessive protein and not enough carbs can be too hard for your kidneys to filter and process, and can lead to poor kidney function.
However, the two major causes of chronic kidney disease are hypertension and diabetes. The keto diet can help control diabetes and hypertension since it encourages low carbs and low sugars. This means you need physician guidance if you already have kidney disease and will need specific modifications to monitor your kidney function closely.
There are also concerns that long-term keto dieting can lead to bone demineralization and osteoporosis. This is still under investigation. Most studies have involved children with epilepsy, which keto diets are shown to improve. Newer studies have shown that there is not a significantly increased risk of poor bone density from a keto diet. The key point is to talk with your physician and check your calcium and Vitamin D levels. Supplement these, especially if you have an increased risk of osteoporosis. Supplementation and exercise along with moderating alcohol intake and avoiding smoking have been shown to decrease the risk of osteoporosis.
What’s the deal with fasting?
Another concept of the keto diet is “intermittent fasting.” Fasting helps access the fat in your body for energy and thus promote weight loss. Again, you should be cautious with this and be sure to talk with your doctor.
Fasting doesn’t have to be a complicated algorithm or days of eating only bone broth. It can be as simple as eating dinner early around 5:30 p.m. and waiting until 6:00 a.m. to eat breakfast. This allows your body to “fast” and access the fat stores for energy rather than eating something else to provide simple sugar for energy.
Ultimately, remember that the key to a healthy lifestyle is not another fad diet — it’s a way of life.
In general, most people eat too many carbs. Changing your plate to include protein, healthy fats, fruits and veggies, very small amounts of starchy carbs and minimal added simple sugars is the key to long-term health. I would challenge you speak to your physician about what dietary changes might be right for you.
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