People go without food or drinks for various reasons—illness, weight loss, lack of food or religion.
While fasting has its benefits, it can be detrimental to your health if it goes for a long time or if one has underlying conditions. Recently, four people died in a bid to starve themselves to “meet Jesus”. Ann Wairimu explores potential effects of going nil by mouth
The exact length of time human beings can survive without food is an open question. The body adapts to fasting by slowing its rate of fuel consumption and even switching the brain to an alternate source of energy. In the first few days, your body begins to waste a variety of fuels, breaking down not only fat, but also protein contained in lean tissue — muscles and vital organs such as the intestines, spleen and kidney — to supply the brain with its preferred fuel, glucose or sugar. As starvation continues, there are other adjustments—metabolic rate goes down, physical activity diminishes and some psychological changes occur. The pulse slows and the blood pressure falls below normal. The final phase of starvation begins when all the body’s fat stores have been exhausted, and protein from muscle and vital organs must be broken down to feed the brain. In many cases, the muscle wall of the heart grows thin, the remaining fibres begin to fracture, and the heart weakens as a pump. The person then slips into a coma because “all of the biological processes get slowed down so much” from lack of fuel.
2. Could weaken the immune system
Fasting has previously been suggested as a useful approach for preventing or managing chronic diseases such as cancer, obesity and heart disease, but results from mouse studies show prolonged fasts may impair the immune system. A New York study recently found that there was a rapid reduction in the number of circulating immune cells in animals that were not allowed to eat in the hours after they awoke. Blood tests comparing these mice with those given a regular diet showed that, on average, the fasting mice had less than 10 per cent of the number of monocytes — a type of white blood cell that helps fight infections and recruits other immune cells to treat injury.
3. Makes you vulnerable to kidney failure
During the initial days of fasting, the body releases large amounts of water and salt in the urine. This process is known as natural diuresis or natriuresis of fasting. If this happens to you and you don’t replace the fluids and electrolytes you lost through urine, you could become dehydrated. A dark-coloured urine may indicate you are dehydrated. Starving oneself of food and water over a long period of time could have adverse effect on the normal functioning of the kidney, which requires some level of water intake to sustain its operation. Dehydration further starves the body cells of water leading to a false rise in the various metabolites in the blood stream. It can also cause retention of some electrolytes and waste products such as urea, creatinine, among others in the blood stream.
4. Can worsen your diabetes
Fasting may impair the action of sugar-regulating hormone insulin, and lead to increased risk of diabetes. If you have diabetes, fasting may make your blood sugar levels to go dangerously low (this is called hypoglycemia). That’s especially true if you take medication such as insulin to control your diabetes. Hypoglycemia can cause you to feel shaky, pass out, or even go into a coma.
5. Damage to cells
Previous research has shown that fasting can produce molecules called free radicals, highly reactive chemicals that can cause damage to cells in the body. One study examined the effects of fasting every other day on the bodyweight, free radical levels and insulin function of normal adult rats over three months. Although the rats’ bodyweight and food intake decreased as expected, the amount of fat tissue in their abdomen actually increased. In addition, cells of the pancreas that release insulin showed damage, while the presence of increased levels of free radicals and markers of insulin resistance were also detected. The results also suggest that in the long-term harm may be caused and that more investigation is needed to assess how people may be affected, particularly those with existing metabolic issues.
6. Fatigue and low energy
Studies show that some people practicing various methods of fasting experience fatigue and low energy levels. Low blood sugar related to intermittent fasting can cause you to feel tired and weak. Plus fasting may lead to sleep disturbances in some people, which can cause tiredness during the day. However, some studies show that intermittent fasting can actually reduce fatigue, especially as your body becomes adapted to regular fasting periods.
7. Bad breath
Bad breath is an unpleasant side effect that can occur in some people during fasting. This is caused by lack of salivary flow and the rise of acetone in the breath. Fasting causes your body to use fat for fuel. Acetone is a by-product of fat metabolism, so it increases in your blood and breath during fasting.
Going 16 hours a day without enough fluid is a recipe for (gastrointestinal) disaster. So if you have started an intermittent fasting diet and can’t seem to get your bowel movements to happen regularly (or at all), it’s time to hit pause.
9. Hair loss
Sudden weight loss or a lack of proper nutrients, especially protein and B vitamins, can cause hair loss. Although some studies suggest calorie restriction can lead to hair loss, more research needs to be done to fully demonstrate this relationship.
10. Changes in your menstrual cycle
Women who lose a dramatic amount of weight or are consistently not getting enough calories every day might find their menstrual cycles slow down or even stop completely, as noted in a 2021 study published in Experimental Gerontology and a 2019 study published in the journal Obesity.