by Loes Kettenis

We do it all: eating. What’s more, we have to! Fortunately most of us love it.
Eating is one of the most important things in our life. Nothing more romantic than a delicious dinner by candlelight, or a picknick in a beautifel spot by the water. In this way we combine eating with pleasure.

By the way why do we eat food? The body sends a signal to the brain that it needs energy. The brain transformes the signal into hungriness. And then we start eating. Food is fuel. Fuel is energy. Energy is needed to keep the processes within the body going. Eating is of vital interest. Breathing, moving, thinking and keeping warm, all this requires energy. Organs such as the heart and the intestine need energy to keep going. When you are sporting you need a lot of energy. Being a couch potato you consume hardly any energy. Children need much energy when growing up.When you are eating more than your body needs the surplus energy is converted to body fat which will be stored as fat tissue. Fat can be a good reserve when times are bad.

Animals
With animals it is roughly the same story. Let’s take lions, predatory carnivores. Most part of the day they are sleeping using up hardly any energy. But during hunting they consume very much energy. After having caught and eaten their kill the energy consumption lessens again by lazing once more, sometimes for days on end. And what about the lions in a zoo? They do not hunt. At most they have to try and find their food that has been hidden. But that requires hardly any energy compared to hunting. That is why lions are put on a diet. Each animal species has its own diet. The one animal species is much more active than the other that is why a diet is specially composed for each of them.

Long intestine
There is a difference between various animal species. The one is a plant-eater (or herbivore), the other is a meat-eater (or carnivore). And another animal species is eating meat as well as plants, being an omnivore. Humans belong to the omnivores. Characteristics for omnivores are a special set of teeth and the length of the intestine. Everything we eat is broken down by our body and masticated. This process is called digestion. The food is broken down into their smallest parts so that the body can use the digested nutrients which are taken up in the blood and dispose of the waste products (undigested parts of the food called fibres).  Digestion of meat is fairly easy. That is why the intestine of a lion is short. Hay and leaves are very difficult to digest therefore the intestine of a herbivore, say a zebra, is very long. The belly of a herbivore containing the intestine seems to be thicker than that of a carnivore. The length of the intestine of an omnivore is in between the two.

Animals and overweight
In zoos much care is taken of the diets for all the animals, but like humans animals may sometimes gain too much weight. Not only because finding food is much easier than in the wild but the composition of the diet offered in captivity will often be different. Many animals are fed with pellets containing the necessary proteins, vitamines and minerals (nutrients) but pellets are very rich. Besides fruit growing in The Netherlands is different from fruit from the tropics. These are some of the factors that may lead to overweight in animals. But when is an animal overweight? How do we measure whether an elephant is overweight or even obese or not.

BMI
With humans you can determine whether they are overweight or not by measuring the BMI (Body Mass Index) determining the proportion ration of length and weight. But try using a measuring tape with an elephant!
With animals the so-called Body Condition Score is used. Vets currently rely on charts to determine  -partly on the basis of look and feel (ribs)- wether animals are overweight or obese. A BCS of  3 means a healthy weight.

Have a look at the pictures of a Body Condition Score of the zebra and the photo. The ribs of the zebra are not visible which means that the values 1 and 2 are counted out. From the hip to the tip of the area near the base of the tail there is no sunken line (values 1 and 2)  and no straight line (value 3), but a bulging line. This means a BCS of 4. So our zebra is slightly overweight. 

Why?
We humans have a wide choice of food. Healthy as well as unhealthy food is available. Unfortunately seasonings such as fat and sugar are unhealthy and very rich. That is why we are at risk to become overweight before long. It is easier for zoo animals. They don’t have to choose because we do it for them. They get a balanced diet so that they keep their proper weight. In case they should gain weight their diet can be adapted.