Why So Much Air in The Tubs?


Ever wondered why sometimes there’s so much air in your supplement tub? Well, under-filling supplement containers is a standard practice in the industry. It is called “slack filling“. 

Often we simply shrug it off because we received the 1kg whey protein we paid for, even though it came in a container that could accommodate 2kg!

However, often consumers take it seriously as they feel that they have been deceived by the large container. Hence the large number of lawsuits in the USA against companies for under-filling their containers, like Iovate Health (the makers of MuscleTech) and GNC. 

What does the law say?

Both US and South African (SANS289) laws permit a degree of slack filling in the following cases: 

  • When it serves a role. For example, air is allowed in a bag of potato chips to protect the content so that on opening the package the consumer gets actual potato chips rather than potato chips powder. This is called “functional slack filling”.
  • Some filling machinery have operational constraints and thus cannot fill containers to the brim.
  • Unavoidable settling of powders in jars during transit and storage. This is especially true for mass gainer products which contain carbohydrate powders. The latter generally have a higher density than the fluffier protein powders, hence the higher possibility of settling.
  • When the container needs to be of a minimum size so that its label can meet labelling requirements (e.g. font size, mandatory information, etc.)    

How much slack filling is allowed?

This is not known. Industry insiders point to about 40%, meaning all is okay as long as the powder occupies at least 60% of the capacity of the container.

Misuse of Slack Filling

Sometimes companies use “non-functional” slack fill especially for protein to trick you into believing that you are getting more. A big tub looks more impressive on the shelves than a smaller tub even though the same amount of powder is in both of them. This is especially true for those who are new to supplements because regular users would know what to look out for (e.g. Net Weight) come purchasing time. 

Some companies have no choice

Sometimes companies, especially smaller ones, have to use a large container for a given amount of powder for the following reasons:

a. It can be a pain in the arse to source and keep inventory of several  container sizes and getting labelling artwork resized accordingly. So, they go for what’s available at jar manufacturers, which sometimes may not be the best fit. 

b. Increasing the amount of powder so that the jar looks more full adds to the cost of the product which affects price-competitiveness. 

But still that’s not an excuse! Legal experts advise companies to understand and select appropriate packaging and not rely on package labels and weight indications as a defence to slack fill allegations, as in most cases these are likely to fail. 

I hope the above helps!

Veeraj Goyaram for Suppsguru.com

Feature image courtesy of Reddit

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Medical disclaimer
The information presented on this website is intended for adults 18 or over. Its aim is purely educational and does not constitute medical advice. Please consult a medical or health professional before you begin any program related to exercise, nutrition, or supplementation especially if you have a medical condition. If you consume any product mentioned on our site, you do so on your own free will, and you knowingly and voluntarily accept the risks.  © 2020. Veeraj Goyaram

About the author

Veeraj Goyaram, MSc Med (Exercise/ Nutr. Science)

My name is Veeraj Goyaram. I am a full time supplements guy and make my living in the world of nutritional supplements.

I am a nutritional product scientist by profession, meaning I create innovative nutritional supplements in the lab (food technology side) based on what I know about the human body and nutrients that affect it.

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