A new study published in the Journal of the International Society of Sports Nutrition shows drinking a beverage with 25 grams of casein (a form of protein from milk) or whey before a morning workout may help burn extra calories, which could lead to weight loss. Casein and whey are types of protein from milk and are found in dairy products such as milk, cheese, yogurt (regular and Greek) and kefir.
Strong evidence supports the idea that eating a protein-rich snack or breakfast before your morning workout increases resting energy expenditure throughout the day (the amount of calories the body burns at rest), but not specifically the source or type of the protein. These scientists investigated which type of protein best increased energy expenditure post workout. In this experiment, researchers tested the hypothesis that casein, more than other forms of protein or carbohydrates or fasting, consumed pre-workout improves energy expenditure post workout.
The study was a small one, which looked at 11 healthy college-age males who performed the same 30-minute, moderate-intensity treadmill jog on four different mornings. They drank a different solution 30 minutes prior to starting each jog and then researchers measured resting energy expenditure (the number of calories the body burns at rest) twice: immediately after each jog and 30 minutes later.
They measured the number of calories burned at rest using a method called indirect calorimetry. Indirect calorimetry measures the amount of carbon dioxide exhaled and oxygen inhaled, which can be used to calculate the amount of calories the body is burning at any one time. This was a double-blind, placebo-controlled trial (which is the gold standard of nutritional and medical sciences), so both the participants and the researchers did not know which solution the participants were given prior to each jog.
Researchers found participants burned up to 300 more calories (based off of a 150-pound male) at rest post workout after drinking the beverage with 25g of casein or whey protein compared to drinking a sugary beverage. While protein pre-workout contributed to greater calories burned than a sugary beverage or fasting, there was not a significant difference between the casein and whey protein shakes. These findings are in line with the existing body of evidence showing protein pre-workout boosts calories burned at rest.
STRENGTHS OF THIS STUDY
- The experimental design was a double-blind, placebo-controlled trial, which is the gold standard of experimental design in nutritional and medical sciences.
- Each participant was compared against himself rather than other participants. This is known as a crossover design.
- Researchers controlled (kept consistent across all morning jogs) for fasting time prior to each jog by instructing participants to fast for 10 hours prior to the next morning’s jog.
- Researchers controlled for exercise and diet the day prior to each workout.
- All participants were physically active but not competitive athletes making these results more applicable to the general population.
- Researchers utilized a small sample size of a mere 11 participants.
- Researchers utilized college-age males making these findings less applicable to females or males of other age groups.
- Researchers controlled for the volume of exercise but not the type of exercise each participant engaged in on a regular basis prior to this experiment.
THE BOTTOM LINE
Drinking 25 grams of casein or whey before a moderate-intensity morning workout may help increase the amount of calories the body burns throughout the day and promote weight loss better than fasting or drinking a sugary sports drink.
Consider eating Greek yogurt or cottage cheese 30–60 minutes before a moderate-intensity jog or workout to boost calories burned throughout the day.