Pros and Cons of the Keto Diet

ketogenic diet

Ketogenic diets are a trending topic. Pinterest and instagram are loaded with recipes oozing with bacon, cheese, butter and coconut oil. Fat, fat and more fat! So what’s the deal with this crazy high fat diet? Proponents of keto diets claim it has numerous health benefits ranging from treatment of Alzheimer’s and certain neurological disorders to weight loss and reversing type 2 diabetes (reference). Keto diets are especially popular in the weight loss, diabetes and PCOS communities due to claims of improving insulin sensitivity, controlling cravings and promoting weight loss. Hype or hope? If eating tons of fat is your thing (or you are curious about it), read on!  Pic credit: ketogenicdietitian on instagram

Pros and Cons of a Ketogenic Diet | Martha McKittrick Nutrition

I became “keto-curious”

Years ago, I was a fat-phobic dietitian due to the brainwashing by the government that fat was “bad”.  Over the years, I’ve totally changed my opinion and am a proponent of fat. But I must say, I was a bit repulsed by this diet and skeptical that it could have ANY health benefits. However, I consider myself open-minded and love learning new things. So I packed my bags (and ski gear!) and headed to a Low Carb Conference in Breckenridge Colorado. Yup – 3 days of learning new research on the ketogenic diet … followed by a few days of skiing of course!

The keto diet peaked my curiosity so I decided to dig in a little deeper. I’m going to do a serious of blog posts on the ketogenic diet. If it’s not up your alley, don’t unsubscribe from my blog as this is NOT the way of eating I promote to 95% of my patients. But I just found it interesting and wanted to share. I also did the ketogenic diet myself for 5 weeks, I’ll blog about that as well. (pic – that is me 3rd from the right. And yes – we were wearing helmets!)

History of ketogenic diets

Ketogenic diet are nothing new. They were originally developed in the 1920’s to treat children with epilepsy. Somehow eating a VERY high fat diet (~80-90% fat) with small amounts of protein and minimal carbs helped reduce seizures in many of these children. Then Atkins made ketosis popular again with the strict induction diet where carbs where to be kept under 20 grams for the first few weeks. These diets kind of went by the wayside for years, but are back again full force. 

What is a keto diet?

Ketogenic diets are high fat, very low carb, and moderate protein diets. They include foods such as butter, coconut oil, olive oil, cheese, heavy cream, avocado, nuts and moderate amounts of protein such as eggs, cheese, meat, poultry, fish and low carb vegetables. Grains, fruits (except for a few berries), sweets, and large portions of most vegetables are not allowed. Pic credit: ketogenicdietitian on instagram

While there are several variations (3:1, 4:1 or modified atkins), the ketogenic diet usually contains 70-75% fat, 15-20% protein and about 5-10% carbs. This comes out to about 25 -50 gm of net carbs a day (up to 50 gm if you are very active). Subtract fiber from total carbs to get net carbs. All ketogenic diets are low carb diets, but not all low carb diets are ketogenic due to the protein restriction. Amino acids in protein can be converted to glucose, which can kick the body out of ketosis. 

So how do keto diets work?

Normally your body runs on glucose. When you go on a ketogenic diet, your blood sugar and insulin levels get low which causes your body to switch from using mainly glucose as fuel to using fat as it’s main source of energy. Ketones are produced when fat is metabolized for energy. This is called ketosis. So basically, the body changes from a sugar burning machine to a fat burning machine. After starting a ketogenic diet, it can take weeks to even months to become fully ketoadapted (using fat purely for fuel). This process can have numerous metabolic effects in the body, including decreased levels of insulin and blood sugar, improved insulin sensitivity and increased fat burning to name a few.

Are keto diets for you?

I’d definitely say this diet is NOT for the average person looking for a healthy diet! In my opinion, they are too restrictive and low in many nutrients, including fiber, fruits, whole grains. legumes and even vegetables. However,  if you are very overweight, especially if you have insulin resistance and type 2 diabetes, it may be an option.  Research is ongoing about the benefits of ketogenic diet for some types of cancer and neurodegenerative diseases. But there are some serious pros and cons to consider. 


1. Very restrictive and may be difficult to adhere to long term. Unlike other low carb diets, even protein and non-starchy vegetables are limited. Can make it difficult to handle social situations as well.
2. Could cause an unhealthy relationship with food.  If you have an eating disorder, disordered eating or an unhealthy relationship with food, this diet is not for you! Women with PCOS have an increased incidence of eating disorders and having so many foods “off limits” might exacerbate this.
3. May lead to keto flu including headache, constipation, lightheadedness, fatigue, poor sleep, and difficulty exercising. This tends to pass within a few days to a few weeks.
4. Can be low in many vitamins, minerals, antioxidants, and fiber
5. May increase risk of kidney stones and osteoporosis
6. May increase cardiovascular risk by raising LDL cholesterol (including small dense LDL) in a subset of people. It is recommended that you track your cholesterol levels, including the more detailed panel that shows particle number and size.
7. Not recommended while pregnant or breastfeeding due to lack of research.
Questionable effects on the gut microbiome. As per Dr. Felice Gersch, high fat diets cause overgrowth of certain types of hostile gut bacteria, which are linked to impaired gut bacteria function as compared to a high fiber, polyphenol rich diet which nourishes the gut microbiome.
9. Please discuss the ketogenic diet with your physician if you have any medical conditions or are taking medications including diabetes or high blood pressure meds as they may need to be adjusted.
10. The long-term safety of the ketogenic diet is yet to be determined.

Potential Benefits

1. Curbs carb cravings and decreases hunger.
2. Increased fat burning and weight loss hypothesized to be from utilization of fat stores for energy and decreased appetite from the ketones (reference). In addition, muscle mass tends to be preserved.

3. Lowers blood sugar and insulin levels.
4. Decreases risk of type 2 diabetes and may even reverse it.
5. May cause less of impact of lowering metabolism, which occurs through dieting 
6. May decrease cardiovascular risk factors by increasing HDL, lowering triglycerides and atherogenic small dense LDL and increasing the size and volume of LDL particles which is considered to reduce cardiovascular disease risk (reference).

7. Lowers blood pressure.
8. More steady supply of energy and “mental clarity” due to more stable blood sugars.

9. Elimination of migraines (reference)
10. Less dependency on certain medications (reference).
11. Improved athletic performance in SOME endurance athletes. While the majority of athletes prefer to fuel with carbs, a small subset finds improved nutritional performance with ketogenic diets. Once the body is ketoadapted, fat can be used for fuel. A fellow cyclist, Chris Colt, (see pic) claims the ketogenic diet improved his performance in the 2017 iconic Leadville 100 mile mountain bike race. The effect of altitude sickness never occurred since he became a keto adapted cyclist. His mental clarity throughout the race was never hindered and did not even know the term “bonk”. The biggest benefit was after with fast recovery and no GI issues.  It is also rumored that Team Skye who won the Tour de France were on keto diets (or some type of low carb high fat diets) 

This is enough fat to chew on for one blog post. 

Stay tuned for:
My article on Pros and Cons of Keto for PCOS in the upcoming PCOS Challenge Magazine
Podcast I did with PCOS Diva on PCOS and Keto … will be airing 1st week in May

My upcoming blog posts on:
– How to Make Your Keto Diet as Healthy as Possible
– My Personal Experience on Keto Diet

Further reading/references:
The Art and Science of Low Carbohydrate Living by Dr. Phinney and Dr. Jeff Volek
The New Atkins for a New You by Dr. Eric Westman
Keto Clarity by Jimmy Moore with Dr. Eric Westman 
Eat Rich, Live Long
by Ivor Cummins and Dr. Jeffry Gerber

Pegah Jalali MS, RD, CNSC, CDN specializes in ketogenic diets. Follow her on instagram: ketogenicdietitian



I especially love problem-solving, whether it’s helping women defeat issues plaguing them for years, helping a busy executive find practical ways to get heart healthy, or providing tips to help you reverse diabetes. That’s why I’m on a constant quest to expand my knowledge by staying on top of the latest research.

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1 Comment

  1. Kara Keto Burn Pills on July 31, 2018 at 12:22 am

    As a Newbie, I am permanently exploring online for articles that can help me.
    Thank you

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