Lifestyle · Medicine

Intermittent Fasting and Keto Diet: What I Learned From My Grand Rounds

It’s been WAY too long since I’ve written a blog post. I have to admit I’ve been extremely checked out since the end of residency. My motivation to use my brain for any higher thinking has been quite low. As I type this I realize this must have been a sign of burnout. Thankfully after returning from a month of traveling I’m feeling energized and back to my normal self.

Moving on to the purpose of this post: sharing what I learned from preparing my grand rounds. I chose to speak about dietary trends for a few reasons: 1.Friends and patients often ask about starting a new diet and I felt uninformed. I didn’t know what the ketogenic diet was about let alone whether I should recommend for or against it. 2. MD’s unfortunately get very little nutrition training in medical school yet nutrition has always been an interest of mine.

My research consisted of reading the latest journal articles as well as briefly trying these diets out for myself. Here’s what I learned:

Intermittent Fasting

What is it: increased time in the fasting state

Goal: to promote the use of stored fat as fuel

Typical day: there are many ways to fast. One popular strategy is an eating “window” where you have 8 hours to eat all of your calories for the day. There is also the 5:2 where you eat normally for 5 days of the week and then eat 500 calories for 2 days. See more examples below…

35922A20-DB21-446E-A52C-4E1A11C98D1D        Untitled copy

My experience:

I tried intermittent fasting personally and had little success. My normal routine involves waking up at 5am to exercise and I found it nearly impossible to exercise vigorously and then eat nothing until noon (I was nearly passing out). So the popular noon-8pm eating window didn’t work for me at all. I then tried to shift the window to eat from 8am-4pm but found myself starving when i got home from work. I’m not willing to give up my routine so intermittent fasting ultimately didn’t work for me.

Evidence: Evidence is conflicting. A recent JAMA article describes obese patients randomized to alternate day fasting. “A day of fasting (eating 25% of normal calorie intake) followed by a day of feasting on 125% of normal calorie intake is as effective for weight loss as daily calorie restriction”

Risks/Benefits:

The good: Many positive effects on hunger hormones (increases insulin sensitivity, positive effect on ghrelin/leptin). Works for people who graze, especially at night or people who enjoy eating larger meals. Less time thinking about food.

The bad: May lead to overeating during feeding times. After all, it’s human nature to reward yourself after hard work i.e. exercising or fasting.  

Bottom line: Can be highly effective for certain people especially those who enjoy grazing, snacking at night, and eating large portions. The fasting window creates a ‘rule’ that puts a stop to those bad habits.

 

Ketogenic Diet

One of the more popular diets out there right now. I have frequently been asked about this diet by patients and friends but didn’t know much about it. Prior to my research, the name ‘Ketogenic’ had a negative connotation given the association between ketosis and dangerous conditions such as diabetic ketoacidosis and malnourished alcoholics.

What is it: low carb, high fat, moderate protein (5% carbs, 75% fat, 20% protein)

Goal: to burn fat (ketosis → gluconeogenesis) rather than burning stored glycogen

Typical day:

  1. Limit carbs to <20g per day (by far the most important thing for ketosis to happen)
  2. Moderate protein <1g/kg/day
  3. Eat enough fat to feel satiated
  4. Avoid snacking
20g-grams-in-two-ways
photo credit: “A Ketogenic Diet for Beginners – The Ultimate Keto Guide.” Diet Doctor, www.dietdoctor.com/low-carb/keto#food.

My experience:

I attempted to follow the keto diet for one day and tracked my macros on myfitnesspal (below). I have to say this was extremely challenging since i discovered that carbs in non-starchy foods add up MUCH faster than I expected. For example, i wanted to eat fruits but didn’t because it put me over my carb limit. Eating vegetables throughout the day caused me to go over the 20g carb limit! I also went over the 20g carbs limit at 1600 calories which really isn’t enough for me. I will admit I was not hungry since i was eating plenty of dietary fats, but ultimately I found this way of eating very restrictive and not sustainable for my lifestyle.

keto sample diet

Evidence:

Evidence comparing low carb vs. low fat vs. low calories diets are conflicting. There are some good quality studies which conclude that low carb diets are more effective for weight loss. Other studies conclude that as long as there is a reduction in calories, weight loss will happen regardless of which macronutrient is emphasized.

Risks/benefits:

The good: There is a quick drop in weight for the first week due to diuretic effect, then people typically see 1-2 lbs lost per week. Encourages lean meat and veggies. Ketosis suppresses hunger.

The bad: Ketosis is meant to be a survival mechanism for your body in times of low glucose. It would theoretically put a lot of stress on the body to constantly be in survival mode. The keto diet decreases fruit consumption and may be difficult to sustain long-term.

Bottom line: Low carb/high fat may be a good option for people who want to lose weight. There is good evidence that limiting carbs leads to weight loss especially considering the typical American diet (high in white flour and sugar). This may ultimately be why low carb diets work in our society: not because of the micronutrients emphasised but simply getting rid of the most calorie-dense part of the american diet.

Can we come to any conclusions? For me, just going through the process of learning about these trendy diets has helped me to better understand my patients.  I wasn’t able to find any ‘magic’ behind these diets but I do believe that they work well for certain people. Most people have something that gets them into trouble when it comes to overeating. If that problem is overdoing it with sweets or breads then keto diet would work well. If the problem is overeating at night or grazing all day then giving yourself a “Feeding window” may prove successful.

 

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