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Friday, August 17, 2018

With obesity rates at an all-time high in the United States (with 40 percent of adults and 19 percent of kids being labeled as obese), there is a barrage of diets being thrown our way in an attempt to slow down this alarmingly increasing rate. People are desperate to lose weight and lose it fast. One such diet on the rise, the ketogenic diet, is the gaining interest of consumers and researchers alike, due to its intrinsic unconventionality. Instead of cutting out fats, one of the infamous dietary culprits behind weight gain, the diet insists on eating more of them. In fact, the ketogenic diet comprises mostly fat and protein intake. It severely restricts carbohydrate (CHO) intake, cutting it down to less than 50 grams (gm) per day. To give you an idea what that means, about 1 ½ cups of blueberries will provide about 25 gm CHO. Though the Atkins diet is similar in concept, the ketogenic diet is more restrictive in its CHO limit.

In usual homeostatic circumstances, the body uses glucose from CHO intake as its main energy source. However, after three to four days of extremely low CHO intake, the body, in a desperate attempt to conjure up energy for normal functioning, starts breaking down fats instead. As a result, the body produces ketone bodies in a process called ketogenesis (which primarily takes place in the liver) and uses them as an energy source. In the first couple of days of this transition, one may start to feel headaches, mental fogginess, dizziness and aggravation. The body is getting used to using fats as its energy source.

The ketogenic diet is actually a veteran in the medical world, being utilized as a method of treatment for drug-resistant pediatric epilepsy. However, more and more research is spilling out onto both the medical and dietary scene that this diet actually promotes weight loss, improves blood sugar and lipid levels, and aids in treating neurological diseases like Alzheimer’s and Parkinson’s disease (though there are no human studies to support this notion).

The exact mechanism connecting the ketogenic diet and weight loss is unclear. However, there are a number of sound theories behind it:

  1. It may be related to the higher satiety effect one receives after eating more protein, thereby decreasing overall food intake.
  2. The diet may affect appetite-control hormones, such as leptin (the hormone that indicates fullness after eating) and ghrelin (the hormone that indicates hunger).
  3. Since fat is the main source of energy, more fat from the body is being “burned,” facilitating weight loss.
  4. Ketogenesis expends a lot of energy (aka calories), also burning more calories and facilitating weight loss as well.

A study conducted by Dashti et al. (2004) wanted to examine long-term effects of the ketogenic diet on obese individuals. Eighty-three patients went on the diet for six months. Results showed significant weight loss; reduction in BMI, total cholesterol, LDL cholesterol, blood glucose levels and triglycerides (TG); and an increase in HDL cholesterol. Another study by Goday et al. (2016) wanted to test the safety and tolerability of the ketogenic diet versus a hypocaloric diet in type 2 diabetic (T2DM) patients. Eighty-nine obese T2DM patients were randomly assigned to either diet. Results showed weight loss, reduction in waist circumference and a reduction in HA1C and blood glucose levels in those patients that pursued the ketogenic diet. A meta-analysis of 13 studies done by Bueno et al. (2013) showed that the ketogenic diet boosts weight loss, lowers TG and blood pressure (BP) levels and increases both HDL and LDL cholesterol levels. A review done by Kosinski and Jornayvaz (2017) indicated that though patients were successful in weight loss, there is controversy in the studies about insulin resistance, diabetes management and improvement in lipid levels.

Even though research has unofficially touted the ketogenic diet as being a successful method for (short-term) weight loss, there are some caveats that should be recognized. The inherent makeup of the diet (carbohydrate restrictive, heavily protein/fat based) makes it difficult to maintain long term. Many (but not all) research studies were short term (three weeks to six months), deeming the diet unrealistic for long-term weight loss and sustaining that weight loss. Also, any diet that blocks out any food groups makes the consumer more susceptible to nutrient deficiencies. If one would like to try this diet, it’s important to ensure that they’re meeting their micronutrient (vitamins/minerals) needs. Lastly, the ketogenic diet may be putting one with chronic kidney disease (CKD) at high risk of damaging the kidneys. Proteins comprise amino acids, nitrogen being one of their core ingredients. When proteins are being metabolized (broken down), they are filtered through the kidneys. Excessive amounts of protein being metabolized can put strain on the kidneys and possibly damage them. Though studies have shown that those without CKD have not shown damage, it’s important to keep this in mind. Before starting any restrictive diet, be sure to talk with a medical professional for any possible contraindications.

By Melissa Papir Kolb, 

MS, RD