Javier Gonzalez Profile picture
Aug 31, 2022 β€’ 13 tweets β€’ 6 min read β€’ Read on X
Great to see this new research out in @IJSNEMJournal led by @timpodlogar

A 🧡 to give a bit more background...

#cycling #LaVuelta22 🍚🍌🚡
1/13
Athletes commonly train almost everyday (and sometimes multiple times a day), so carbohydrate stores are often being depleted and need replenishing.

A goal of a pre-competition breakfast is to keep carbohydrate stores (glycogen) topped up
2/13
This is particularly important as our carbohydrate stores are relatively limited (vs fat stores).

journals.lww.com/acsm-essr/Full…

Yet carbs are essential for maintaining prolonged, high-intensity (top-end) performance.
3/13
Breakfast is a special meal for our liver glycogen (more than muscle glycogen).

This is because liver glycogen is depleted overnight as liberated glucose provides fuel for the brain while we fast.

So, does breakfast matter if we are taking on board carbs during exercise?
4/13
A: Yes! A high-carbohydrate pre-exercise meal can increase capacity for moderate-to-high intensity exercise, even when we are consuming carbohydrates during exercise
5/13
So what about the types of carbohydrate to include in the breakfast?

Some of the main types of carbs can be seen below. Most cereals (e.g. pasta and rice) will be polysaccharides (chains of glucose molecules).

🍝🍚

Fructose though, is a bit special...
6/13
After exercise, ingesting fructose-containing carbs (e.g. sucrose) can accelerate (by up to 2-fold!) the replenishment of liver glycogen stores
7/13

pubmed.ncbi.nlm.nih.gov/27013608/
And this happens without compromising muscle glycogen
8/13
This is probably because of the special way in which fructose is metabolised in the liver
9/13

physoc.onlinelibrary.wiley.com/doi/epdf/10.11…
Another potential benefit of ingesting fructose alongside glucose-based carbohydrates is providing a separate route for carbohydrate absorption in the gut (i.e. more rapid total CHO absorption)
10/13
So based on this background, it was hypothesised that adding fructose to a carbohydrate-rich breakfast might increase exercise capacity.

To test this, cyclists were provided with rice-based breakfasts with added glucose or fructose (to match for total carbohydrate) 11/13
Interestingly, exercise capacity was increased by ~5% with the rice+fructose versus the rice+glucose

journals.humankinetics.com/view/journals/…

12/13
I would note that many athletes already add fructose at their breakfast (either intentionally or unintentionally).

Often science provides evidence for (and sometimes against) what athletes already do in practice.

Most condiments on this table contain fructose... 13/13

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More from @Gonzalez_JT

Aug 5
What happens if people restrict either dietary #sugar or all carbohydrates (#ketogenic diet)?

🍝vs🍬vsπŸ₯“

Our latest πŸ“ assessed energy expenditure πŸƒβ€β™€οΈ, energy intake 🍽️ metabolism 🩸πŸ’ͺ🏻 and other outcomes

A 🧡

πŸ”—

#lowcarb #keto #diet #food doi.org/10.1016/j.xcrm…

Image
Image
What did we ask people to do and did they do it?

People were asked to stick to these 3 diets

They could eat as much/as little as they liked as long as they stuck to these ratios

Urinary ketones confirmed people were in ketosis on the low carb (LOWCHO) diet Image
Another compliance marker was respiratory exchange ratio (RER)

This was lowered by lowcarb in
1)the fasted state 🍽️
2) postprandial state πŸ₯˜
and 3) during exercise πŸƒβ€β™€οΈ

doi.org/10.1016/j.xcrm…
Image
Read 19 tweets
Mar 31, 2023
Should people be concerned with blood glucose concentrations if they don’t have prediabetes or diabetes?
1/10

#glucose #health #biohack #science #metabolism #cgms #hba1c #sugarspikes
For context, the relationship between LDL-cholesterol concentration and coronary heart disease risk appears linear across the entire physiological range

What about glucose?
2/10
For glucose, it might depend how it’s measured:

STANDARDISED TESTS (reflect underlying physiology)
-Fasting [glucose]
-2-h [glucose] post-OGTT

FREE-LIVING MEASURES (reflect underlying physiology x acute behaviour)
-HbA1c
-CGMS variables

What do the data show?
3/10
Read 10 tweets
Feb 23, 2023
If you start running daily and burn 500 kcals on theπŸƒβ€β™€οΈwill this increase total daily calorie burn by 500 kcals or not?

Yes = ADDITIVE (Panel A)
No = CONSTRAINED (Panel B)

Take the pollπŸ‘‡ & read the 🧡to find out more
1/14
#metabolism #energy
Does increasing physical activity directly add to total energy expenditure (ADDITIVE)

or

is total energy expenditure constrained by compensatory reductions in other components (CONSTRAINED)?
2/14
This question has become increasingly discussed over recent years.

Our latest paper critiques the evidence for and against these models.

πŸ”—doi.org/10.1016/j.advn…

Big team effort from @DrDylanThompson @GregLJMU @Alan_Batterham
3/14
Read 14 tweets
Dec 8, 2022
De Novo Lipogenesis (DNL) is the production of fat (lipids) from other sources

E.g., conversion of sugars to fats

So what happens to DNL if calorie intake is restricted?

A 🧡that might surprise you...
1/8

doi.org/10.1113/JP2777…
#fasting #science #nutrition #metabolism
First, a quick poll before reading on

If mice 🐁 are calorie restricted 🍽️ for a prolonged period of time (provided 30% fewer calories than they would choose to eat normally at baseline), what will happen to DNL?
2/8
The Q is a bit vague to have a clear A, as it depends if we are talking about DNL in liver, adipose tissue, or the whole body.

Before we delve into those areas, its worth noting that mice do lose weight when restricting calories by 30%

πŸ”—doi.org/10.1152%2Fajpe…
3/8
Read 8 tweets
Nov 30, 2022
How can carbohydrate metabolism be measured during exercise?

πŸπŸŒπŸžπŸπŸšπŸš΄β€β™€οΈπŸš΄β€β™‚οΈβ›ΉοΈβ›ΉοΈβ€β™‚οΈ

New #openaccess review by @AndyJKing & I in @IJSNEMJournal

Hopefully a useful resource for people researching & reading about exercise metabolism πŸ‘©β€πŸ”¬πŸ“–

A summary🧡1/12

doi.org/10.1123/ijsnem…
What are isotope tracers?

Molecules where certain elements (e.g. Carbon) differ in some ways (mass) but less so in others (function)

This means we can distinguish between "label" and naturally occurring molecules, whilst the label behaves similarly to the natural molecule
2/12
Molecules (e.g. glucose) can be labelled in different ways.

e.g. just one carbon could be labelled (13C) in a specific position

or all the carbons could be labelled (13C), known as uniformly or universally labelled (U-13C)
3/12
Read 12 tweets
Nov 3, 2022
Restricting total carbs has a much bigger effect than just restricting sugars in the first 24 hours

Check out our latest study (led by @AaronHengist) on carb and sugar restriction 🧡 (1/11)

doi.org/10.1007/s00394…

#lchf #lowcarb #carbs #highfat #keto #ketogenic #diet #health
The main aim was to see if restricting sugars or total carbs alters physical activity levels

This is because previous studies suggested fasting can lower physical activity & this can happen quickly

We wanted to know if this was due to carbs or energy

What did we find?
2/11
25 people (15 female) ate 3 diets for 24 hours with a variety of metabolic and energy balance measures
3/11
Read 11 tweets

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