Skip to main content
Eating Habits and Time
Jan 1, 2005

“The things that I fear most for my people are being overweight, sleeping too much, laziness and a lack of deep faith.” 1
Prophet Muhammad (peace and blessings be upon him)

Effective time management occurs only when we force ourselves to perform important activities within a plan so that we can reach our goals. Goal setting and planning our activities are important steps in this. But if we fail to engage in these activities and to finish them, then we end up with an unfulfilled plan on our hands. Our mind-body is the only vehicle through which we can accomplish our goals in life. Our eating habits, including the type and amount of food we eat, affect our mind-body in many ways, such as our energy and stress level and our sleep patterns. Hence, it is crucial to examine the impact of eating habits on our mind-body. It is notable that time-management literature’s vast majority pays little or no attention to this aspect of mind-body control. In this article we will consider three factors in this respect: The impact of the amount of food we eat, the timing of meals, and the nature of our food.

“Limit eating, limit sleeping, limit talking. This is the path to the spiritual life.” – Sufi proverb

The Impact of How Much We Eat and Drink

There is little mention of eating habits in time-management literature. However, our eating habits affect our management of time in many different ways. Let us first consider the times of our day that are immediately affected by our eating and drinking habits:

1. Food preparation or waiting time,

2. Eating/drinking time,

3. Digestion and mental recovery time after the meal,

4. The time spent in the lavatory, and finally

5. The extra sleep we may need after a heavy meal.

It is easy to see that the impact of each of these factors is proportional to the size of the meal. The more food we prepare or ask for, the longer the preparation/waiting time will be. More food also takes longer to eat. The next stage, which is very important, is the time needed for digestion and mental recovery after the meal. Depending on the type and amount of food we intake, the digestion time can range from one hour up to three or four hours. When the amount of food is great, our digestive system competes with our brain for the limited amount of sugar in our body. This may prevent our brain from functioning at its peak. Consequently, we may experience a lack of focus, a lack of energy, or we may feel sleepy. Most people try to compensate for such feelings by drinking caffeinated beverages, which have their own disadvantages.

The time we spend in the lavatory is also proportional to the amount of food we eat. When we eat more, our visits are more frequent and more time is spent there. Eating foods that are rich in fiber is also another cause of frequent visits to the lavatory. But a diet deficient in fiber is not healthy, so the way to cut back on time spent there is not to cut back on fiber-rich foods, but rather to cut back on the amount of food we eat.

Finally, the type and the amount of food we eat affect our sleep patterns. First, when we eat more, we need to sleep longer. It is no coincidence that people who overeat also tend to oversleep. But the impact is not limited to sleeping time alone. Stimulating foods or drinks near bedtime disturb our sleep patterns and cause us to benefit less from our sleep. This, in turn, results in our efficiency being affected the following morning.

When we consider all these factors, we begin to realize how overeating makes self-management difficult and we can understand the wisdom behind the prophetic saying “No human being has ever filled a container that is worse than his stomach. . .”2

The Impact of What We Eat and Drink

In addition to the amount of food, the type of food we eat is also important. Certain types of food may energize our brain, while certain others make it sluggish.3 In order to increase one’s energy levels, nutritionists recommend a balanced diet that is devoid of harmful substances. An important property of the food we eat is what is known as the “glycemic index.”4

The Glycemic Index of Foods

Since sugar is the substance that gives us energy, many people are under the false assumption that the more sugar we consume, the more energetic we feel. This view, however, fails to account for the compensatory balance in our body. When we consume large amounts of sugar, either in the form of pure sugar, or via foods that are rich in sugar, the amount of sugar in our blood stream increases. Our body responds to this situation by secreting insulin into the blood stream, reducing the amount of sugar. If the increase in the sugar level is very steep, than the body reacts strongly to reduce it and causes the sugar level to fall to a very low level. This is why we feel sluggish for some time after consuming sugar-rich foods.

In order to avoid the down-time of insulin compensation, nutritionists recommend that we avoid foods that are high in simple sugars and which have a high glycemic index in carbohydrates. The “glycemic index” measures how much the levels of circulating blood sugar increase within a few hours after eating a particular food. Examples of foods and drinks with lots of simple sugars include cookies, cakes and other baked goods, candy bars, sodas, and fruit juices. These foods and drinks include large amounts of simple sugars, such as glucose or fructose. Initially, they give us a quick energy boost. In the longer term, however, the body’s monitoring system increases the levels of insulin in the blood and hence we experience a quick decline shortly after this boost. The brain can only use glucose for energy. When the glucose level drops in the blood, the brain cannot perform at its peak. We may end up feeling even more drained than before we ate or drank. In order to maximize brainpower and mental focus, we need to minimize fluctuations of blood sugar by selecting foods with lower glycemic index numbers. These will break down more slowly and release glucose gradually into your bloodstream. The insulin response will also be more gradual and we will not suffer a mental down time. The following table shows the glycemic indices of certain foods:

The Interaction of Food with Hormones

Our food intake also influences the release of important hormones, such as serotonin, melatonin, and dopamine. Serotonin gives us feelings of well-being, personal security, and relaxation. A shortage of serotonin may leave us feeling very tired, needing excessive sleep, with feelings of low self-esteem, causing negative thinking, and maybe even difficulty in concentrating. However, excessive levels of serotonin are also harmful.

Melatonin is a hormone that is believed to be involved in the regulation of sleep. Melatonin secretion is significantly higher at night, although some is produced during the day. The pineal gland, where melatonin is produced, functions as a biological clock by increasing its output of melatonin at night by more than ten times. This increase in secretion begins around sunset and reaches a peak at around 2 a.m. After this peak, it falls to a low level by the time of sunrise. High levels of melatonin can induce drowsiness.

Dopamine stimulates alertness and awareness. However, excess levels can cause an increased heart rate, muscular tension, and disrupt sleep patterns, as well as resulting in shortened attention span and excessive self-confidence. Excess levels of dopamine have been associated with ADHD (Attention Deficit Hyperactivity Disorder) and risk-taking behavior.

Serotonin, melatonin, and dopamine are constantly being produced in our bodies. But we can increase or decrease their levels by changing our habits. Our eating habits, spiritual well-being, and activity all affect the hormone chemistry in our bloodstream and in our brain. These in turn affect our moods and tendencies.5 This is one reason why we can feel differently about the same task at different times of the day. Carbohydrates, for instance, can alter the level of serotonin in our brains and bring on feelings of calm and relaxation. While these effects can be desirable at night, they are certainly not what we want when we need to increase our energy level. Certain proteins can help increase levels of dopamine. Thus, we may prefer a menu rich in proteins rather than carbohydrates before a mentally demanding task. In the evening, some hours before we go to bed, we may want to avoid stimulating foods as they may interfere with our sleep. If our sleep is affected, we may wake up drowsy and drained.

The Impact of Caffeinated Drinks

Although caffeine can induce a short-term stimulation to our body and mind, it will also cause a negative rebound effect. Furthermore, in the long run the brain adapts to caffeine intake and may not be able to function at its peak when we do not supply it with the accustomed levels of caffeine. This is an unhealthy dependency. If you are already used to taking caffeine regularly to boost your energy, work on slowly eliminating it from your diet. Decaffeinated coffee and tea may help get rid of the addiction while maintaining a placebo effect. One advice for a quick lunch that will not deplete your energy, but rather increase it, is to eat pure protein. Tyrosine, one of the amino acids in protein, is well known for its ability to increase levels of alertness and energy levels. Foods such as broiled fish, sliced poultry, boiled eggs, or tuna are good sources of tyrosine.

Additional advice from nutritionists to prevent fatigue includes getting enough iron, taking advantage of herbs, and preferring natural foods over artificial ones.


In this article we have addressed a commonly overlooked aspect of time management: The impact of our eating habits on self-control and productivity. In addition to its negative consequences on our health, eating too much also affects how we make use of our time. Overeating is one of the primary causes for excessive sleep, fatigue, and loss of mental energy. Foods rich in simple sugars in particular are responsible for dips in performance shortly after consumption. The type of food we eat and the timing of our meals also impact our mind-body. Various hormones that affect our performance are affected by our nutrition pattern. In the prophetic saying we quoted above, Prophet Muhammad, peace and blessings be upon him, links excessive sleep, laziness, and a lack of reflection with overeating. It is remarkable that such sound medical advice came from a person who lived in the 7th century. The recommendation in this prophetic tradition is fully applicable today: Moderate eating is the key to self-control and effective time management. 


  1. Suyuti, Jam’ul Jamawi, 832.
  2. Tirmidhi, Zuhd 47; Ibn Maja, At’ima, 50.
  3. Chafetz, M., Smart for Life, Penguin Books, New York: 1992.
  4. Jennie Brand-Miller et al., The New Glucose Revolution -
  5. Complete Guide to Glycemic Index Values, Marlowe & Company, New York: 2003.
  6. Kotulak, R., Inside The Brain: Revolutionary Discoveries of How the Mind Works, Andrews McMeel Publishing, Kansas City: 1997.