Why Swimming Makes You Hungry? (Temperature, Appetite and More)

If you’re among the people who experience an increase in appetite after swimming, know that you’re not alone. It’s actually quite common. Many of us, who have been for a swim, even for a short period, know how bad it can be; you feel like you can eat everything in sight… but why? 

Researchers are not quite sure why swimming makes us more hungry. It is believed that, while swimming, the cooler temperature of water affects certain hormones in our body, making us more hungry. Swimming in cooler water can also increase our metabolic rates, which can lead to higher hunger levels.

Interestingly enough swimming does not burn as many calories as other cardiovascular activities like cycling or jogging. So, what exactly makes swimming so different? Why spending time in the water makes us feel hungry? 

First Things First; Why Do We Feel Hungry?

When you feel hungry, you know how hard it is to ignore that feeling. Suddenly nothing seems as important as getting ourselves a nice warm meal.

Hunger is one of the most basic and most powerful instincts we have. It’s is the way for our body to force us to find food in order to grow and develop when we are young, to survive, stay alive, and recover after physical activities or injuries.

Therefore, hunger is the result of eating less than what our body needs to function correctly. However, there are certain exceptions.

What Makes Us Feel Hungry?

There are two major hormones that regulate how hungry we feel:

1. Ghrelin

Ghrelin is a hormone that is secreted by cells found in the stomach and intestine. When our levels of ghrelin are higher, we feel more hungry, and higher levels of ghrelin are associated with increased obesity.

Usually, when our stomach is empty, ghrelin levels spike up, that way we will feel hungrier and eat, after which ghrelin levels go down.

Researchers have found that the concentration of acylated ghrelin during swimming stayed low. Because of that, most of the swimmers might not feel increased hunger while swimming (sometimes this is referred to as exercise-induced anorexia). Interestingly enough, ghrelin did not spike after swimming.

2. Leptin

Leptin’s role is to suppress appetite. It is produced in the fat cells in our body. The more fat we have stored in our bodies, the higher levels of leptin we will generally have. So, if we have more body fat – we should be less hungry. However, a lot of obese people tend to develop resistance to the effects of leptin.

Furthermore, working out has been shown to decrease leptin levels in our bodies.

Why Does Swimming Make Us Feel Hungry?

Even today, studies are inconclusive, and researchers are not quite sure why swimming makes us feel so hungry every time. Swimming is not more intensive than running or cycling, but after swimming, we can feel like we haven’t eaten in a week.

Several theories are suspected to influence our perceived hunger levels:

1. Swimming Is a physical activity.

Any intense physical activity is going to lead to a faster onset of hunger. Swimming is one such activity, just like riding a bicycle or jogging. However, it cannot be ignored that swimming can make us feel a lot hungrier even compared to other more intense activities performed for longer periods.

Is our body tricking itself it feels hungrier or do we really need more calories after swimming? Unfortunately, due to the nature of swimming, it has proven hard for scientists to study it more deeply.

2. The temperature of water can make a difference.

The temperature of the water is usually cooler than our bodies. And since we are not wearing any protective clothing, our body cools down a lot faster. This can lead to blood vessels in the skin constricting. It is suspected that as a result, specific hormones which regulate our appetite will be suppressed.

The “International Journal of Sports Nutrition and Exercise Metabolism” decided to investigate what exactly happens with our body when we exercise in warm water vs. cold water. As we will find out, the results were more than thought-provoking.

Two groups of people were formed and asked to exercise for 45 minutes on a stationary bicycle, which was submerged underwater.

  • The first group was exercising in warm water with a temperature of 91.4 degrees Fahrenheit (or 33 Celsius).
  • The second group was exercising in cold water that was 68 degrees Fahrenheit (or 20 Celsius).

These are the numbers – the people who exercised in cold water burned on average 517 calories and the people in warm water 505 calories. Are the extra 12 calories really that much of a difference? (Just as a fun reference – a slice of whole wheat bread is about 70 calories on average!)

I feel like you will agree with me that we can kind of write off the difference.

And here comes the really interesting findings.

The group that exercised in the colder water consumed on average 44% more calories than the group that trained in the warmer water.

However swimming in water with a moderate temperature (82.4 – 83.3 Fahrenheit, or 28 – 28.5 Celsius) showed no significant increases in perceived hunger.

3. Metabolic rate.

Another factor that may play a role is that our metabolic rate increases if we are submerged in cold water. This increases our energy expenditure and, as a result, we feel a lot more hungry. The same effect happens if we are exposed to cold air.

Also, we should not forget that, usually, swimmers don’t eat before exercising.

The general advice here has been to give yourself at least 2 hours for more substantial meals and about 30 minutes for smaller meals before doing any swimming exercises. Two hours is not a small amount of time considering that you will be doing some intense full-body workouts.

Can We Prevent Hunger After Swimming?  

So, what can we do to keep hunger under control after swimming?

1. Be mindful about the food you eat.

Since you’ll be more susceptible to your increase in appetite, you’ll need to be very mindful about what you will eat. Different types of foods can have different effects on our perceived levels of hunger and fullness.

For instance, certain foods can trick your brain into thinking you didn’t eat enough, while, in reality, it might be quite the opposite. These are certain examples:

  • Fried foods tend to make us feel like we have consumed fewer calories than what we have.
  • Fiber-rich food takes longer to digest. As a result, we feel fuller for longer while consuming a fewer amount of calories in the process.
  • Foods with a higher glycemic index (GI) are broken down by our body at a much faster rate than food with a lower GI. They are digested a lot faster; therefore, it’ll take less time before we feel hungry again.
  • Something that might do the trick is to keep a small protein bar in your swim bag and eat it right after you get out of the water. This can help to reduce hunger levels before you get back home.
  • Drinking lots of water after swimming is another great way to make your stomach feel fuller.

2. Increase your body temperature after swimming.

The acute effect of hunger can be mitigated to a particular extent by increasing your body temperature after swimming. This can be done in various ways like soaking in a hot tub or taking a brisk walk for 15 minutes.

3. Swimming in warmer water

Swimming in warmer water (82.4 – 91.4 Fahrenheit, or 28 – 33 Celsius) has not been associated with higher hunger levels. Avoiding swimming in cooler water might be a good strategy to prevent overeating.