Javier Gonzalez Profile picture
Nov 3 ā€¢ 11 tweets ā€¢ 6 min read
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 šŸ§µ (1/11)

doi.org/10.1007/s00394ā€¦

#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
Fuel use changed rapidly

Low-carb increase fat oxidation šŸ”„ and decreased carb oxidation within hours

Restricting just sugars made little difference šŸ¬
4/11
Similarly, blood sugar and insulin responses didnt differ much with sugar restriction but were much lower with total carb restriction.

This might be surprising but makes sense with the knowledge that table sugar has a lower glycemic index than many non-sugar carbs šŸ¬šŸš
5/11
One of the only differences with sugar restriction was blood lactate concentrations

Probably because fructose is converted into lactate by the liver and thereby provides fuel for the brain and muscle šŸ§  šŸ’ŖšŸ»
6/11
Levels of fat in the blood were higher after the low-carb, high-fat breakfast, and were lower the following morning when fasted

This likely reflects increased fat oxidation šŸ”„
7/11
Ketosis was rapidly induced by the low-carb diet, especially in women

Remarkably, women also showed increased LDL-cholesterol within 24 h of low-carb šŸ³šŸ„“
8/11
Despite these large changes in metabolism, differences in physical activity and energy intake were pretty much absent

9/11
Summary

Restricting total carbs affects metabolism rapidly and more drastically than just restricting sugars

Some effects were larger in women than men

Energy balance (short-term) was unaffected

Stay tuned for the 12-week data!
10/11
Thanks to @rankprize @UniofBath & Cosun Nutrition Center for funding, and participants for their efforts!

11/11

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More from @Gonzalez_JT

Oct 22
Why do some people "backload" carbs?

What does this mean and what is the science behind it?

A šŸ§µ 1/12

#exercise #carbs #lowcarb #lchf Image
"Carb backloading" is the practice of avoiding carbs early in the day and eating them later in the day, usually after some exercise.

Why would this make sense to do?
2/12 Image
Some rationalise this based on evidence that after exercise, muscle glycogen levels are ā¬‡ļø and muscle glucose uptake is ā¬†ļø.

Ingested carbs can therefore restore glycogen.

ā¬†ļø muscle glucose uptake should mean our blood glucose remains low right?

doi.org/10.1152/jappl.ā€¦
3/12 Image
Read 12 tweets
Oct 16
There is no evidence that sugar directly causes any negative health effects.

Is this true?

A šŸ§µ
#sugar #health #metabolism
1/10
Latest UK guidelines suggest there is only sufficient evidence that diets high in sugars:

1) cause increased calorie intake
2) are associated with tooth decay

So if calorie intake is not maintained, there are no harmful effects of sugars?

2/10

assets.publishing.service.gov.uk/government/uplā€¦
Absence of evidence is not evidence of absence, but we also should be careful about believing anything with weak or little evidence.

So what does the evidence show?
3/10
Read 10 tweets
Oct 11
Do doses of fat respond the same way as glucose?

A šŸ§µ 1/8

#metabolism #fat #nutrition #diet
This time, the measure of interest is the level of fat in the blood (triacylglycerol; aka TAG)

When fasted, levels of TAG are low (left)

High levels of TAG make the plasma part of blood look cloudy/turgid (right)

2/8
In contrast to glucose, the more fat eaten in a meal, the higher the level of TAG

Does the type of fat matter?

3/8
Read 8 tweets
Oct 7
Which fuels do human foetuses use?

This may surprise you... (1/5)šŸ§µ
First, how do we even know what the human foetus uses as a fuel?

The amount of carbon dioxide released relative to the amount of oxygen used (aka RER or RQ) is a good marker of fuel use.

But how can this be measured in a human foetus?
2/5
With some clever techniques, scientists in 1927 sampled blood from arteries delivering blood to the foetus and veins draining blood from the foetus

By measuring the O2 & CO2 concentrations, RQ could be calculated
3/5

doi.org/10.1016/S0002-ā€¦
Read 5 tweets
Oct 3
Which of these will produce the biggest blood sugar response?

75 g glucose alone

75 g glucose + 7.5 g fructose?

šŸ§µ 1/8
Adding 7.5 g fructose to 75 g glucose reduces the blood glucose response.

Since this is more total carbohydrate ingested with 75 g glucose + 7.5 fructose why is the blood glucose response lower? 2/8

pubmed.ncbi.nlm.nih.gov/11134101/
I'll get to that in a moment, but I assume people may also want to know if this effect holds true in people with type 2 diabetes?

Yes it does.

Lower glucose and insulin responses when fructose is added to an oral glucose tolerance test 3/8

diabetesjournals.org/care/article/2ā€¦
Read 8 tweets
Oct 2
Q: Which of these would produce biggest the blood sugar response?
(i.e., biggest change in glucose concentration)

Answers below (1/8) šŸ§µ #glucose #health #metabolism
Have a guess here before reading on to find out if you are right... (2/8)
A: There is no meaningful difference (at least in healthy people) - data from: pubmed.ncbi.nlm.nih.gov/28684634/

How can 75 g glucose (3 times more) not increase glucose more than 25 g?

(3/8)
Read 8 tweets

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