Lactose and sucrose as fuel during exercise
What it found
In 11 people cycling for 150 minutes, lactose and sucrose were broken down and used as fuel at similar rates.
Lactose led to more fat burning and less use of the body's own carbohydrate stores than sucrose.
What they found
Studies in people
Fuel from lactose
The rate at which the body burned the sugars was similar for lactose and sucrose. On average, lactose was burned at 0.56 grams per minute and sucrose at 0.61 grams per minute.
Body's own carbs
The body used less of its own stored carbohydrate for energy when people drank lactose compared with sucrose or water. With lactose, stored carbs provided 38% of energy, versus 50% for both sucrose and water.
Fat burning
Fat provided more of the energy when people drank lactose than when they drank sucrose. Fat contributed 42% of energy with lactose and 28% with sucrose.
Blood sugar and insulin
Blood sugar rose with both lactose and sucrose compared with water. Insulin rose more with sucrose than with water, and lactose was in between.
Stomach comfort
Most people had minimal stomach or gut symptoms with any drink. One person dropped out after severe symptoms (diarrhea and stomach pain) during the lactose trial, and another had milder symptoms after lactose.
Breath hydrogen
Breath hydrogen, a sign of undigested sugar reaching the gut, went down after exercise with sucrose and water. With lactose it went up in some people and down in others, but the average change was not significant.
What the authors conclude
“Lactose and sucrose exhibited similar exogenous CHO oxidation rates during exercise at moderate ingestion rates.”
Also in their conclusions
- They say that lactose and sucrose are oxidized at similar rates during exercise when taken at moderate amounts.
- They note that lactose led to higher fat burning and lower use of the body's own carbohydrate stores compared with sucrose.
- They suggest future studies should look at whether lactose can improve exercise performance and whether it works at higher doses.
How it was done
Sucrose and other fast-burning carbohydrates are known to improve endurance performance when taken during exercise. The authors wanted to know whether lactose, the sugar in milk and yoghurt, could also be used as a fuel source during exercise.
Eleven recreationally active people (8 men, 3 women) cycled at a moderate intensity for 150 minutes on five separate occasions. On each occasion they drank either lactose, sucrose or water, and the researchers measured how much of the sugar was burned for energy and took blood samples.
What it can’t tell you
- This was a small study with 11 people, so the results may not apply to everyone.
- The study measured how the body uses the sugars during exercise, not whether lactose improves performance.
- The authors did not test higher amounts of lactose or longer exercise bouts.
Who paid
- Funding
- Funded by Biotechnology and Biological Sciences Research Council (from the PubMed record).
- Authors work at
- University of Birmingham, UNITED KINGDOM
The paper
- Title
- Comparable Exogenous Carbohydrate Oxidation from Lactose or Sucrose during Exercise
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Odell OJ, Podlogar T, Wallis GA (2020). Comparable Exogenous Carbohydrate Oxidation from Lactose or Sucrose during Exercise. Medicine and science in sports and exercise. doi:10.1249/MSS.0000000000002426Free full textPubMed 32520875DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error