Food Safety Food Manager

A Comprehensive Guide To FAT TOM–What Is It, And Why Does It Matter?

Posted by
Trust20 Contributors • 5 minute read

Whether you're a seasoned chef or a new kitchen manager, understanding the basics of food spoilage is essential to running a successful business. Spoiled food not only tastes bad but can also make people sick, which can have detrimental effects on your business.

This is where FAT TOM comes in.

First things first–this is an acronym, not a derogatory or offensive reference to any specific person. This acronym is a handy tool that can help you remember the six factors contributing to the growth of harmful bacteria in food that make it unsafe to eat.

In this article, we will cover the principles of FAT TOM listed below, why they matter, and action steps for foodservice professionals. You can jump to each section by clicking the links below.


What are the FAT TOM principles?

FAT TOM stands for Food, Acidity, Temperature, Time, Oxygen, and Moisture. All of these factors are critical to understanding the context of how they contribute to food spoilage. Food spoilage can refer to any change in a food that causes it to lose flavor (at best) or become unsafe to consume (at worst).

Those two metrics, of course, are different, but as a foodservice professional, you need to understand that both are caused by the growth of microbes, like mold and bacteria, in food. The good news? Customers aren't all that likely to get sick from smelly or moldy food - because they probably won't eat it in the first place (although you'll probably get at least one or two awful Yelp reviews as a result).

However, the more dangerous component of this comes from pathogens that lead to food poisoning. These bacteria often don't produce any smell, discoloration, or changes. You won't know until it's too late that the food was contaminated - not until you start experiencing signs like nausea, cramping, or diarrhea.

That's why using FAT TOM is essential to keep food safe. Let's break down the six factors of this acronym and discuss how they contribute to food spoilage.


Bacteria need nutrients to survive and multiply. This means that perishable foods like meat, dairy products, and vegetables are the perfect breeding ground for harmful bacteria. However, some foods are more likely to spoil than others.

Fruits, starches, and vegetables can all succumb to bacteria and spoilage, but high-protein foods like meat, milk, poultry, seafood, and eggs are more likely to harbor pathogens. These must always be kept in the refrigerator or freezer (or preserved in some way, like via canning or smoking). You can keep foods like bread and apples at room temperature because it will take them much longer to spoil.

Action Steps for Foodservice Professionals:
  • Understand which foods have a higher likelihood of spoilage 

  • Make sure food is stored properly

  • Know what cross-contamination looks like and take steps to avoid it


The level of acidity in food can also contribute to spoilage.

Bacteria grow best in a neutral pH environment, around 7.0. Foods with a low pH (around 4.6 or below), like pickles and fruit juice, are less likely to spoil because the acid makes it difficult for bacteria to survive. 

Anything with a pH lower than 4.5 typically doesn't need to be refrigerated. 

Foods with a high pH generally include vegetables and meats. Brussels sprouts, for instance, have a pH of around 6.00 to 6.30.  

Action Steps for Foodservice Professionals:
  • Know the pH of different foods

  • Cook food at high temperatures and store it at appropriate temperatures as well

  • Check expiration dates

  • Look for dents, leaks, bulges, or rust in canned foods before consuming, serving, or preparing


Temperature is perhaps the most critical factor when it comes to food spoilage. 

Bacteria grow rapidly in a temperature range between 41°F and 135°F, also known as the "temperature danger zone." Bacteria need a moderate temperature (that "41°F to 135°F" range) to survive. If it's too cold, they don't reproduce; if they're too hot, they die.

Keeping food above or below this temperature range can slow down or stop bacterial growth, making it safe to eat. 

Action Steps for Foodservice Professionals:
  • Familiarize yourself with Temperature Danger Zone (TDZ) and follow it

  • Don't leave food at room temperature for too long 

  • Store food at the correct temperature 


The longer food stays in the danger zone, the more time bacteria have to multiply. This is why it's important to keep track of how long food has been sitting out at room temperature. Food that has been in the danger zone for more than four hours should be discarded.

Action Steps for Foodservice Professionals:
  • Don't keep food at the TDZ for more than four hours 


While some bacteria need oxygen to survive, others grow best in an oxygen-free environment. Vacuum sealing and canning are popular methods of oxygen-free food storage, but be aware that certain types of harmful bacteria can still grow in these conditions. Confit is another technique that removes oxygen to ensure food safety. 

Action Steps for Foodservice Professionals:
  • Keep food covered 

  • Consider preservation techniques like vacuum sealing, canning, or confit to extend the freshness and safety of sensitive foods


Moisture is the last factor in the FAT TOM acronym and plays a significant role in food spoilage. 

Just like us, bacteria need water to survive. Bacteria thrive in moist environments, especially those with high water activity (the amount of available water in food). That is why it's important to keep food dry and properly stored. 

Certain foods, like uncooked rice and dried beans, have had their moisture removed, meaning they can last for a long time–even years. The staying power of dehydrated foods is why dehydration is such a popular method of food preservation.

Action Steps for Foodservice Professionals:
  • Make sure you store food at the correct temperatures

  • Take steps to reduce moisture in foods, such as dehydration, or by using oxygen absorbers in food storage containers

  • Keep surfaces clean and dry to prevent moisture that can lead to bacterial growth

Why do the FAT TOM principles matter?

Following the FAT TOM principles is essential to preventing foodborne illnesses and ensuring food quality remains high for consumption. Implementing these principles into your food handling practices means handling food with care, storing it properly, and always cooking it to the right temperature. 

Keeping everyone safe from food contamination doesn’t have to be complicated. With the right knowledge–and helpful mnemonic devices like FAT TOM–every customer can have a safe and enjoyable dining experience.

New call-to-action