Habitual protein intake may explain 'no effect' of insect protein supplementation, study says

The preliminary study demonstrated a non-significant effect between treatment groups - an observation explained by the habitual high protein intake of the young men featured in the study as well as the small sample size.

Using protein isolate extracted from the lesser mealworm (Alphitobius diaperinus​), these men enrolled in the first-of-its-kind trial to see if any physical improvements to eight weeks of resistance training could be gained using insect protein as the main protein source. 

“With a growing world population and increased need for dietary protein, insect protein should be considered a valuable alternative to other dietary animal protein sources given its environmental profile,”​ said the researchers, led by Aarhus University’s Mathias Vangsoe.

“We found that eight weeks of resistance training effectively promote gains in fat- and bone- free mass (FBFM) and muscle strength in healthy young men with a habitual intake of protein corresponding to the general population of young Danish men. ​

“However, no difference in morphological adaptations such as hypertrophy or muscle strength was observed between supplementation groups, as hypothesised.”​

Lesser mealworm protein source​

Insect protein isolate has been touted as a climate-friendly animal protein source, for environmentally conscious athletes, who seek to enhance muscle growth and strength.

Its widespread adoption though will largely be determined by its ability to promote the physical changes demonstrated by popular isolated protein sources consumed today such as whey and casein.

A high-quality protein is one that contains a large amount of essential amino acids (EAA) and branched-chained amino acids (BCAA), especially leucine.

Amino acid (AA) profile research shows that protein from the lesser mealworm equally matches the profile of soybean in regards to EAA,

Differences in quality between whey, casein, and soy protein found greater advantages for whey protein due to AA content, digestibility, and bioavailability.

While insect protein seems to match soy protein in terms of AA content, digestibility and bioavailability might be more similar to whey as it is also an animal protein. 

Study details ​

Led by senior author and associate professor Mette Hansen, the team from Aarhus University enrolled 18 healthy young men, who performed resistance training four days a week for eight weeks.

Subjects were randomised to consume either an insect protein isolate or isocaloric carbohydrate within one hour after training or pre-sleep on training days.

Strength and body composition were measured before and after intervention to detect adaptions to the resistance training.

Three-day weighed dietary records were also completed before and during intervention.

Results found fat- and bone- free mass (FBFM) improved significantly in both groups (control group (Con): (2.5 kg), protein group (Pro): (2.7 kg)).

In trying to explain their observations, the researchers believed that high habitual protein intake in both study groups may partly explain the muted effect of insect protein supplementation.

“On non-training days, Con increased total energy intake from 2764 kcal (Pre) to 3069 kcal (Mid) and Pro decreased from 3142 kcal (Pre) to 2785 kcal (Mid),”​ the study wrote

According to the researchers, this reflected different changes in fat mass (FM) between groups (Con: 0.2 kg, Pro: −0.4 kg).

A small decrease in total energy intake in Pro might be of concern, as a similar study showed that a total positive energy balance is necessary to maintain optimal anabolic processes and attenuate catabolism.

Therefore, group differences in energy balance might also explain why no difference in strength and hypertrophy was detected between groups.

However, it should be noted that variations within the dietary records may exist because of the relatively short registration periods of three days.

Nevertheless, the observed decrease in total energy intake in Pro may also be explained by a higher satiety when consuming the protein bars compared to the carbohydrate bars.

Source: Nutrients ​

Published online ahead of print: doi: 10.3390/nu10030335​​

“Effects of Insect Protein Supplementation during Resistance Training on Changes in Muscle Mass and Strength in Young Men.”​

Authors: Mathias Vangsoe, Malte Joergensen, Lars-Henrik L. Heckmann and Mette Hansen