Intermittent fasting has become super trendy. But is it even worth it? Food is a way of life, and we can’t survive without it.
There are several types of intermittent fasting. You can have one meal a day or fast on alternate days. Another option is to eat very little calories – about 500 to 600 – two days a week. On the other days, eating is normal. Or, fasting can be restricted by time, during specific hours of the day.1 It all depends on preference.
Unlike most diets, intermittent fasting is about when you should eat – not what. There aren’t food restrictions. No wonder it’s so popular!
Yet, you might wonder if it’s safe or right for you. Before reaching for your calendar, learn about the pros and cons of intermittent fasting.
1. Protects Against Oxidative Stress
Calorie restriction results in a short period of oxidative stress. You might think, “Isn’t this dangerous”? Not at all!
Because it’s brief, the oxidative stress sparks a protective response. Your body works to adapt. Later on, it’ll be better at protecting you from oxidative stress.2
This is good news for your overall health. Remember, oxidative stress is responsible for countless chronic diseases. Hypertension, heart failure, sleep apnea, and cancer are just a few examples.3
In a way, caloric restriction gives your body a chance to practice. But they key word is “intermittent.” If fasting lasts too long, it can do more harm than good.
2. Reduces Inflammation
The brief state of oxidative stress has another benefit. As your cells adapt, your body’s antioxidant pathways flourish. In turn, your cells get better at lowering inflammation.4
The result? Enhanced disease resistance. Oxidative stress and inflammation are connected, after all. They both contribute to chronic conditions like cancer and heart disease.5
It can even help patients with asthma – an inflammatory condition. In a study by Free Radical Biology and Medicine, overweight adults followed an alternate day calorie restriction diet. They all had moderate asthma. By the end, there was an improvement in both weight and asthma symptoms.6
3. Enhances Heart Health
As inflammation decreases, cardiac health increases. This may be useful if you have a high risk for heart disease.
Intermittent fasting acts on an enzyme called cholesterol 7 alpha-hydroxylase. It increases the expression of this enzyme, which forces cholesterol to be used for bile – a digestive fluid. The result is better cholesterol levels.7
In rats, intermittent fasting also reduces resting blood pressure and heart rate. The higher resistance to oxidative stress also protects against heart-damaging stressors.8
4. Improves Insulin Resistance
Rat studies have also shown potential for diabetes prevention. In a study by The Journal of Nutrition, intermittent fasting lead to a decrease in blood glucose. Insulin sensitivity also improved.9
Again, this relates to oxidative stress. A brief period induces favorable insulin levels, which keep diabetes at bay.10
5. Maintains Weight
Weight control looks different for everyone. For some, intermittent fasting may be one technique.11
When you limit calories, your body uses fat for energy. This burns fat tissue and sparks a small amount of weight loss.12
1. Leads To Hunger
Despite the pros, hunger is a big hurdle.13 You’re bound to end up with a grumbling stomach.
Everyone reacts to hunger differently. You may feel weak, dizzy, or tired. It’ll also be hard to focus and concentrate, making it hard to work or drive a car.
2. Increases Appetite
Intermittent fasting can make you hungrier. This is probably exactly what you don’t want!
During fasting, the “hunger hormone” ghrelin shoots up. And when you eat? Leptin – the satiety hormone – increases. This suppresses your appetite and helps you eat less.16
3. Prompts Starvation
Continuous fasting can be dangerous. Your body will starve, leading to malnutrition and poor immunity. In extreme cases, it can even cause organ damage.
You might also go into starvation mode. The lesser you eat, the more calories your body needs. This slows down metabolism, making it harder to lose weight.17 Our body tries to hang onto what it has.
Remember, carbohydrates are the main source of energy. Once that’s gone, protein is next. When you stop fasting, your body makes up for it with fat, leading to weight gain.18
This is in extreme cases. However, there is no established safe level of fasting. More research is needed.19
4. Maintains Weight For Short-Term
This effect also has its downsides. Intermittent fasting may be great for a bit, but it’s not ideal for the long-term.
Sure, it has similar effects to continuous energy restriction. But that doesn’t mean it’s better. Continuous energy restriction calls for lower caloric intake while keeping it within a normal range.20 Plus, it isn’t super stressful for your body, so it’s healthier.
With intermittent fasting, your body can’t fully adapt to energy restriction. It also won’t improve overall weight loss efficiency.21
Before trying intermittent fasting, talk to your doctor. It’ll affect each person differently. Your current health status and diseases will determine its safety.
|↑1||Patterson, Ruth E., Gail A. Laughlin, Dorothy D. Sears, Andrea Z. LaCroix, Catherine Marinac, Linda C. Gallo, Sheri J. Hartman et al. “Intermittent fasting and human metabolic health.” Journal of the Academy of Nutrition and Dietetics 115, no. 8 (2015): 1203.|
|↑2, ↑10||Wegman, Martin P., Michael H. Guo, Douglas M. Bennion, Meena N. Shankar, Stephen M. Chrzanowski, Leslie A. Goldberg, Jinze Xu et al. “Practicality of intermittent fasting in humans and its effect on oxidative stress and genes related to aging and metabolism.” Rejuvenation research 18, no. 2 (2015): 162-172.|
|↑3, ↑5||Oxidative Stress/Inflammation and Heart, Lung, Blood, and Sleep Disorders. National Heart, Lung, and Blood Institute.|
|↑4, ↑6, ↑16||Johnson, James B., Warren Summer, Roy G. Cutler, Bronwen Martin, Dong-Hoon Hyun, Vishwa D. Dixit, Michelle Pearson et al. “Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma.” Free Radical Biology and Medicine 42, no. 5 (2007): 665-674.|
|↑7||Longo, Valter D., and Satchidananda Panda. “Fasting, circadian rhythms, and time-restricted feeding in healthy lifespan.” Cell metabolism 23, no. 6 (2016): 1048-1059.|
|↑8, ↑9||Wan, Ruiqian, Simonetta Camandola, and Mark P. Mattson. “Intermittent food deprivation improves cardiovascular and neuroendocrine responses to stress in rats.” The Journal of nutrition 133, no. 6 (2003): 1921-1929.|
|↑11, ↑13||Johnstone, A. “Fasting for weight loss: an effective strategy or latest dieting trend?.” International Journal of Obesity 39, no. 5 (2015): 727-733.|
|↑12, ↑17, ↑19||Horne, Benjamin D., Joseph B. Muhlestein, and Jeffrey L. Anderson. “Health effects of intermittent fasting: hormesis or harm? A systematic review.” The American journal of clinical nutrition 102, no. 2 (2015): 464-470.|
|↑14||Blood Sugar. MedlinePlus.|
|↑15||Low Blood Glucose (Hypoglycemia). National Institute of Diabetes and Digestive and Kidney Diseases.|
|↑18||Berg, J. M., J. L. Tymoczko, and L. Stryer. “Food Intake and Starvation Induce Metabolic Changes.” Biochemistry, (2002).|
|↑20, ↑21||Seimon, Radhika V., Jessica A. Roekenes, Jessica Zibellini, Benjamin Zhu, Alice A. Gibson, Andrew P. Hills, Rachel E. Wood, Neil A. King, Nuala M. Byrne, and Amanda Sainsbury. “Do intermittent diets provide physiological benefits over continuous diets for weight loss? A systematic review of clinical trials.” Molecular and cellular endocrinology 418 (2015): 153-172.|