Six myths about endurance carb fuelling.

Endurance fuelling is one of the most over-marketed corners of sports nutrition. The science underneath it is, mostly, settled. Here are six claims you'll see on packaging or in forums, and what the literature actually says.

1. The gut can only absorb 60 g of carbs per hour.

True for a single-transporter carb (glucose alone). False the moment you add fructose. Glucose uses SGLT1; fructose uses GLUT5. Run both transporters in parallel and trained athletes hit 90–120 g/h reliably (Jeukendrup, 2014). The 60 g ceiling is a 1980s number that survived because it was useful for selling one-carb gels.

2. Carbs make you fat.

Energy balance makes you fat. During exercise, carbohydrate is the dominant substrate above ~65% VO2max — you are burning it as you ingest it. If you eat 90 g/h on a 3-hour ride, you've used most of it before you're off the bike.

3. Maltodextrin is processed garbage.

Maltodextrin is short chains of glucose. Your gut hydrolyses it to glucose in seconds. It exists because pure glucose is hygroscopic and tastes aggressive; maltodextrin gives you the same monosaccharide hit with lower osmolality and a cleaner mouthfeel. Same fuel, better delivery.

4. Fructose is poison.

Excess fructose, consumed at rest, in a hypercaloric diet, raises hepatic de novo lipogenesis (Stanhope, 2015). That is the meaningful concern. During exercise, fructose is metabolised in the liver to glucose and lactate and used as fuel within minutes. The dose, the timing, and the metabolic state are doing all the work.

5. "Natural" sugars are better than "added" sugars.

Chemically identical. The fructose in an apple and the fructose in a sachet are the same molecule. The apple comes with fibre and water, which is great at the breakfast table and a liability at race pace. On the bike you want the sugar without the fibre.

6. Just eat a banana.

A medium banana is about 25 g of carbs. At 90 g/h you'd need almost four bananas an hour, plus salt, plus water you can actually drink while breathing hard. Whole foods are great recovery food. They are a poor delivery system mid-effort.

None of this is controversial inside the field. It's only controversial on packaging, where vague is profitable.