‘Pie hole’, colloquial for one’s mouth, is believed to have evolved in the USA in the 1980s from the British expression ‘cake hole’ (coined in the mid 20th century). Pie hole refers to a mouth, as in: Shut your pie hole or, in this case: Put less in your pie hole.

Wednesday, February 6, 2019

Are Your Mushrooms Tripping Vitamin D?

It's winter in the northern hemisphere, so it's a perfect time to talk about vitamin D, affectionately nicknamed the sunshine vitamin. Without further ado, let's talk vitamin D.

While researching a different article, I found some great, and fun info about vitamin D from an unlikely source... Mushrooms. Intrigued?

Some mushrooms are specially grown to contain vitamin D, perhaps you've seen them at your local supermarket. But how?

Here's what you need to know about your mighty, meaty, magical friend, the mushroom:
  • They contain a vitamin D precursor called ergosterol
  • When ergosterol is exposed to UV light it is converted to vitamin D (just like in your body - more on that later)
  • Wild mushrooms naturally contain vitamin D because they are exposed to the sun 
  • Commercial mushrooms are like your unfriendly hoarder neighbour... in the dark, therefore not exposed to sun
  • Commercial mushrooms that contain vitamin D do so because they are exposed to UV lamps after harvesting
    • A serve (90g/3oz) of these mushrooms contain ~400IU (international units) of vitamin D
    • For reference, most adults need 600 IU/day
If you don't buy the vitamin D-enhanced mushrooms, there is a poor man's solution...! It's all about letting the sun shine where the sun don't shine... Take your mushies outside and turn them upside down, gills (called lamellae) facing up, leave for 15 minutes. Benefits of mushroom sunbathing:
  • They will produce between 200-800IU of vitamin D
  • They may dry out a little or have mild discolouration, but they retain >90% of the vitamin D even after stored and cooked
Some information on vitamin D:
Estimating vitamin D status has some challenges because sun exposure affects vitamin D status, not just food intake. While there are some food sources of vitamin D, it's not as easy to obtain from food compared to other vitamins and minerals. See the table below for food sources.
Source: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h5
How is vitamin D synthesised in the body?
When skin is exposed to UV B radiation, a cholesterol metabolite in the skin produces vitamin D3. But it's not that simple... Your friendly liver and the kidneys are needed to perform a conversion (called hydroxylation) to produce the biologically active form of vitamin D. Voila.

Spend a little time exposing yourself to the sun each day
What did we learn?
  • Mushrooms can provide vitamin D
    • If they are grown and exposed to UV light commercially
    • If you expose their lamellae to sunlight (sounds dirty... get it, coz mushroom grow in dirt?)
  • Your skin, liver, and kidneys are the players that convert sunlight into vitamin D

Wednesday, December 19, 2018

Being Held Up By Keto Bandito?


The keto diet is so popular right now for weight loss... It seemed only fitting that I return from maternity leave with a topic shrouded in controversy. Dieters and wannabe nutrition "experts" tout this diet for weight loss and fat burning. But does the science agree?

Below is Q&A about the keto diet. I hope I've buttered you up enough to chew the fat with me as we explore the fats... I mean facts.

Question #1 - What is the origin of the ketogenic diet?
The ketogenic diet was originally developed as medical nutrition therapy for children with epilepsy. Further, some research shows a keto diet may benefit people with certain cancers, and neurological conditions. In these cases, the diet is administered as therapy under the guidance of a dietitian and doctor.

Question #2 - What is ketosis?
"Keto" is a super cool name, who wouldn't want to say they're on the keto diet? It's almost as catchy as gluten-free. But what is ketosis? To understand it we need to rewind, get a little technical, and understand some physiology:
  • Our brain needs carbohydrates for energy
  • Glucose is the simplest carbohydrate, and the brain's preferred energy source
  • When we decrease our carbohydrate consumption dramatically (to ~20g of carbs per day) our body uses up its glucose stores (glycogen)
No, you're not in ketosis yet.
  • Your body is using amino acids (the building blocks of protein) to create glucose, a process called gluconeogenesis (remember for later)
  • The body is no longer able to manufacture a compound called oxaloacetate, needed for normal fat breakdown via the Krebs/Citric Acid Cycle 
    • Insufficient oxaloacetate means another compound, called acetyl-CoA, builds up 
    • Acetyl-CoAs interact with each other and form ketone bodies: acetoacetate (AcAc), β-hydroxybutyric acid (BHB) and acetone
    • Ketones are formed in the liver but the liver cannot actually utilise them for energy
      • Amino acids are used to create new glucose (gluconeogenesis, remember?)
      • Glycerol is also used to make new glucose, glycerol is liberated during the breakdown of triglycerides (fats stored in your body)
    • Ketones can cross the blood brain barrier and are used as an alternate energy source
Bottom line: The process of producing ketones and remaining in ketosis is complex and requires very strict and precise carbohydrate (and protein) restriction.
Question #3 - Is it hard to maintain ketosis?
Yes. The classic keto diet requires 4% of calories come from carbohydrates, 6% from protein, and 90% from fat. That's <20g of carbs per day. To put that in perspective, it is currently recommended that 45-65% of calories should come from carbohydrates (>50% whole grain), 10-35% from protein, and 20-35% from fat.

There are a variety of keto diet adaptations, however, in my research for this article it's clear that larger amounts of carbs and protein hinder ketosis.
Unlikely to keep you in ketosis

It's really difficult to achieve and actually maintain ketosis. Keto is a very restrictive diet, requiring precise monitoring and weighing of foods. Too many carbs means the citric acid cycle can function normally to break down fats without producing ketones (described in Q#2). Too much protein and your body will convert the amino acids into glucose (gluconeogenesis).

Bottom line: Chances are higher than not that you are not actually maintaining ketosis.

Question #4 - Is ketosis beneficial for weight loss?
Yes, BUT... 

There is significant weight loss at the onset of the keto diet (up to 10lbs in 2 weeks). This is due to water loss (glucose is stored with water, water is heavy.) Most people want to lose fat, not water. No one ever asked "do I look watery in this outfit?"

Due to the restrictive nature of the keto diet, long term compliance is low. Meaning dieters "fall off the bandwagon", and it's well documented weight regain is common in such scenarios. Think about it... you go back to eating normally, glycogen stores are replenished... glycogen contains water, remember? 

Some research shows greater weight loss with the keto diet compared to other diets. This research is specific to obese patients with ongoing physician monitoring.

Bottom line: The keto diet, if maintained beyond 2 weeks often does result in weight (and eventually fat) loss, but the cost is high - see Q#6. And there's a difference between weight loss and fat loss.

Question #5 - How does ketosis help with weight and health?
These are some proposed mechanisms of action:
  • Appetite reduction due to the satiating effect of protein, effect on hormones controlling hunger, the possible effect ketones have on suppressing hunger (1, 2, 3)
  • Reduced lipogenesis (creation of fats) and increased lipolysis (fat breakdown) (1, 2, 3)
There is research documenting possible improvements in blood pressure, insulin sensitivity, and glycemic control.

Bottom line: The exact way weight/fat loss is achieved isn't fully understood, it's likely a combination of factors. 

Question #6 - Are there side effects to the keto diet?
Yes. Ranging from constipation to malnutrition. Deficiencies in calcium, vitamin D, selenium, magnesium, phosphorus, iron, essential fatty acids and prebiotics. Both constipation and deficiencies are due to the scarcity of fiber-containing foods that also contain vitamins and minerals (fruits, vegetables, whole grains, and legumes.) 

Many research papers and articles written by experts cite the importance of monitoring renal (kidney) function. How many of your gym buddies do this?

Ketones raise the pH of blood and a side effect of this is the removal of calcium from bones, called demineralisation which, over time increases the risk of osteoporosis. 

Another side effect is high levels of LDL cholesterol - the "bad" cholesterol (1, 2). This is not a surprise when one's diet is a scoop of fat with a side of fat.

Bottom line: Eating meat, butter, and oil will leave you
Insert face-palm emoji
constipated and lacking many vitamins and minerals needed to maintain proper health and function. Such high-fat diets tend to contain large amounts of saturated fat...BOOM, high LDL cholesterol.

Question #7 - Should you start or continue the keto diet?
To keep this somewhat unbiased, instead of answering the question, here's a checklist to ask yourself:
  1. Is it enjoyable to follow a very restrictive diet?
  2. Do you want to cut out things you enjoy eating?
  3. Think about what you know of a healthy diet. Does it seem healthy to eat huge quantities of fat and miniscule amounts of other things that have stood the test of time like fruit, veg, whole grains, legumes?
If I were answering this checklist, here are my dietitian-biased answers:
  1. Blech, no. I don't want to weigh my food, count my calories, or cut my carbs.
  2. Hell no. I love foods from every food group, especially chocolate (that's a food group, right?)
  3. Umm, no. I do not regularly eat sticks of butter.
    You're probably not...

Wednesday, July 25, 2018

Are You Into Intermittent Fasting?

Intermittent fasting is a hot-button topic, and a popular trend in the weight-loss arena. A recent study shed some light on the science and efficacy of such a dietary pattern. So, should you fastidiously fast the fat away?

As usual, there's more to the story than the click-baity article titles fooling you with follies for fast fat loss.

Intermittent fasting is a broad term covering diets including: 
  • Start-stop eating where people fast completely for 24 hours once or twice a week
  • The 5:2 diet where participants choose one or two non-consecutive days and consume only ~500kcals on those days and eat normally on the other days
  • The 16/8 pattern where people eat only during an 8 hour window, the other 16 hours are fasted
This last pattern involving the 8 hour eating window is where we'll wander today.

A new study found that participants who followed this eating pattern for 12 weeks had the following results compared to those following their usual diets:
  • An approximate 3% loss of body weight
  • An approximate kcal deficit of 300kcal per day (hence the above weight loss)
  • Participants reduced their eating window on average by 3 hours (from 11 to 8 hours)
    • Though research shows only 15% of adults have an eating window <12 hours 
  • A significant decrease in systolic blood pressure 
A few other noteworthy mentions:
  • This study was performed with an obese population
    • Meaning results are not applicable to other populations (eg: normal-weight or overweight individuals) without more research
  • This diet pattern involved no calorie counting
    • A great thing considering counting calories is often inaccurate, time-consuming, not sustainable for a long period, and creates a preoccupation with food
  • The feeding window in this study was 10am-6pm
  • Participant adherence to this eating pattern was positive
    • Meaning this type of dietary pattern shows promise of being sustainable over a long period, compared to alternate-day fasting (like 5:2), or ridiculous diets like "no sugar" or "no chocolate" that cause rebound-like effects when dieters inevitably "fall off the wagon"
  • Compared to other forms of intermittent fasting, this period of time restriction produced a lower energy deficit (meaning less weight was lost) 
    • For example: emerging evidence shows alternate-day fasting produces a deficit of 25-30% of daily calories compared to the time-restricted window that produced ~20% deficit
    • The likely reason is that alternate-day fasting requires strict monitoring and calorie counting where time-restricted fasting does not, as the saying goes "work smarter, not harder"
  • Other cardiometabolic factors (eg: glucose control, insulin sensitivity, triglycerides, cholesterol levels) didn't reach statistically significant levels of improvement 
    • However, the obese population studied had baseline cardiometabolic markers within normal ranges. Therefore, it's quite possible that repeating this study in obese people whose markers are abnormal would see improvement
Lastly, we can't have a conversation about time-restricted eating, as exhibited in this study without mentioning the body clock (circadian rhythm). A previous Pie Hole article details the research on our internal rhythm and how it is impacted by the time of day we eat, drink, and sleep. The timing of food has flow-on effects that can alter metabolism and the microbiome. Research shows a shorter eating window (of <12 hours) helps improve sleep quality, weight loss, weight maintenance, and energy levels.

What are the take home messages?
  1. Shortening your eating window to <12 hours can have many health benefits including higher sleep quality, this in turn impacts metabolism and hormones related to hunger, thus weight
  2. Shortening your eating window is sustainable:
    • It doesn't require calorie counting or strict "dieting" which can lead to a preoccupation with food, increase the risk of disordered eating, and lead to weight regain
    • Long term sustainability means greater adherence to the eating pattern, less "falling off the bandwagon", more positive and long term results 
  3. Put less in your pie hole during a window of 12 (or less) hours per day