Does Intermittent Fasting Work?
Dr. Kate Dudek • December 23, 2020 • 5 min read
Obesity is a major global health issue. The World Health Organisation estimates that worldwide, over 650 million adults are obese. Most developed countries have overweight and obesity prevalence rates approaching 50% and within the MENA region it is estimated that 30% of the population is obese. With increasing obesity rates, comes higher rates of type 2 diabetes and heart disease globally, putting a major strain on health services and medical provisions.
Invasive surgical approaches to counteract the obesity crisis are not suitable for all. Perhaps a better option is to improve education on healthy weight loss programmes, with a better understanding of the dietary approaches currently available.
At one time, dieting involved a daily restriction of calorie intake. This is a technique that works for many; however, questions remain over its long-term applicability. Is it feasible for people to live in a perpetual state of calorie counting? Once people stop restricting their calories, many find that they rapidly regain the weight they have lost. Intermittent fasting may provide an alternative option for those who struggle with long term adherence to traditional calorie restriction.
What is intermittent fasting?
Intermittent fasting is classed as a diet, but is, more accurately, an eating pattern, comprising of periods of fasting and periods of eating ad libitum (“at one’s pleasure”).
There are three main fasting methods:
- 16/8 method (time-restricted feeding). People who follow this approach fast for 16 hours and eat for 8 hours. In fact, whilst 16 hours is suggested, those who do time-restricted feeding fast for anything from 12 to 21 hours. It is the most popular form of intermittent fasting.
- Eat-stop-eat (alternate day fasting). This concept involves fasting for 24 hour periods, once or twice a week. Although participants can eat what they like on the non-fast days, studies suggest that most people naturally reduce their calorie intake on the days in between.
- 5:2 diet (modified fasting). Those who adopt this approach reduce their energy intake by 70-75% for two non-consecutive days each week. On the fasting days they limit themselves to between 500 and 600 calories, eating ad libitum on the remaining days.
Does it work?
There are a number of ‘fad’ diets available today, popularised by celebrities, bloggers and the media. The problem with many of these diets is that they are lacking the scientific evidence to support their claims. For a detailed review on some of the most well known of these diets, click here.
So, how does intermittent fasting compare? Is it just another fad, or is it a realistic alternative to the days of stringent calorie counting and abstinence?
Well, preliminary results are encouraging. Studies have demonstrated that the weight loss observed after 2 – 3 weeks of intermittent fasting is comparable to that seen with daily calorie restriction. It also seems to be equally effective at modulating obesity-associated disease risk, for example, lowering blood pressure and reducing the levels of insulin and glucose in the blood. When considering trials that looked at intermittent fasting, 73% of them had participants that experienced a statistically significant reduction in weight. Although, differences between the studies makes cross-comparison difficult.
The major issue is that there are a limited number of human studies looking at the effectiveness of intermittent fasting, meaning there is a shortage of evidence-based support for the process. Much of the work on the effects of fasting to date, has been performed using animals, which, whilst encouraging, can not definitively replicate the complexity of the human body. Safety data is also lacking, as are studies exploring which type of fasting regime is most effective. It has been proposed that intermittent fasting can improve cognitive performance and cardiovascular outcomes; however, this is yet to be confirmed experimentally.
Take home message
Intermittent fasting may turn out to be a weight management tool that helps to tackle the global burden of obesity. It is an appealing option for those who struggle with the concept of constant dieting; and, despite the fact that ‘normal’ eating is encouraged on non-fast days or for non-fast hours, most people naturally eat more healthily, thus, lowering their calorie consumption. For those that skip breakfast, there is no evidence that they consume more at lunch time to compensate. Considering the positive results from studies such as these, initial results are encouraging. However, the scientific evidence is currently lacking in terms of longer-term human studies.
Provided the fasting is not excessive, side effects are minimal, possibly involving headaches, weakness, dehydration and hunger pangs, although these should be short-lived. However, if the fast is practiced too frequently, or over consecutive days, there is a risk of malnutrition and in extreme cases, organ damage. Thus, it is essential to fast safely and follow the recommended guidelines for your regime of choice.
Nabta is reshaping women’s healthcare. We support women with their personal health journeys, from everyday wellbeing to the uniquely female experiences of fertility, pregnancy, and menopause.
Get in touch if you have any questions about this article or any aspect of women’s health. We’re here for you.
Sources:
- Horne, Benjamin D, et al. “Health Effects of Intermittent Fasting: Hormesis or Harm? A Systematic Review.” The American Journal of Clinical Nutrition, vol. 102, no. 2, Aug. 2015, pp. 464–470., doi:10.3945/ajcn.115.109553.
- Johnstone, A. “Fasting for Weight Loss: an Effective Strategy or Latest Dieting Trend?” International Journal of Obesity, vol. 39, no. 5, May 2015, pp. 727–733., doi:10.1038/ijo.2014.214.
- “Obesity and Overweight.” World Health Organization, https://www.who.int/en/news-room/fact-sheets/detail/obesity-and-overweight.
- Patterson, Ruth E., and Dorothy D. Sears. “Metabolic Effects of Intermittent Fasting.” Annual Review of Nutrition, vol. 37, no. 1, 21 Aug. 2017, pp. 371–393., doi:10.1146/annurev-nutr-071816-064634.
- Templeman, Iain, et al. “The Role of Intermittent Fasting and Meal Timing in Weight Management and Metabolic Health.” Proceedings of the Nutrition Society, 26 Apr. 2019, pp. 1–12., doi:10.1017/s0029665119000636.
- Varady, K. A. “Intermittent versus Daily Calorie Restriction: Which Diet Regimen Is More Effective for Weight Loss?” Obesity Reviews, vol. 12, no. 7, July 2011, pp. e593–601., doi:10.1111/j.1467-789x.2011.00873.x.
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7 Healthy Eating Tips for Postpartum Weight Loss In 2024
Your new baby has arrived, and you are eager to get back into shape. However, [losing weight after pregnancy](https://nabtahealth.com/articles/7-healthy-eating-tips-for-postpartum-weight-loss/) takes time and patience, especially because your body is still undergoing many hormonal and metabolic changes. Most women will lose half their baby weight by 6-weeks postpartum and return to their pre-pregnancy weight by 6 months after delivery. For long-term results, keep the following tips in mind. Prior to beginning any diet or exercise, [please consult with your physician](https://nabtahealth.okadoc.com/). 1\. **Dieting too soon is unhealthy.** Dieting too soon can delay your recovery time and make you more tired. Your body needs time to heal from labor and delivery. Try not to be so hard on yourself during the first 6 weeks postpartum. 2\. **Be realistic**. Set realistic and attainable goals. It is healthy to lose 1-2 pounds per week. Don’t go on a strict, restrictive diet. Women need a minimum of 1,200 calories a day to remain healthy, and most women need more than that — between 1,500 and 2,200 calories a day — to keep up their energy and prevent mood swings. And if you’re nursing, you need a bare minimum of 1,800 calories a day to nourish both yourself and your baby. 3\. **Move it**. There are many benefits to exercise. Exercise can promote weight loss when combined with a reduced calorie diet. Physical activity can also restore your muscle strength and tone. Exercise can condition your abdominal muscles, improve your mood, and help prevent and promote recovery from postpartum depression. 4\. **Breastfeed**. In addition to the many benefits of breastfeeding for your baby, it will also help you lose weight faster. Women who gain a reasonable amount of weight and breastfeed exclusively are more likely to lose all weight six months after giving birth. Experts also estimate that women who breastfeed retain 2 kilograms (4.4 pounds) less than women who don’t breastfeed at six months after giving birth. 5\. **Hydrate**. Drink 8 or 9 cups of liquids a day. Drinking water helps your body flush out toxins as you are losing weight. Limit drinks like sodas, juices, and other fluids with sugar and calories. They can add up and keep you from losing weight. 6. **Don’t skip meals**. Don’t skip meals in an attempt to lose weight. It won’t help, because you’ll be more likely to binge at other meals. Skipping meals will also make you feel tired and grouchy. With a new baby, it can be difficult to find time to eat. Rather than fitting in three big meals, focus on eating five to six small meals a day with healthy snacks in between. 7\. **Eat the rainbow.** Stock up on your whole grains, fruits, and vegetables. Consuming more fruits and vegetables along with whole grains and lean meats, nuts, and beans is a safe and healthy diet. ose weight after postpartum Is one of the biggest challenge women face worldwidely. Different Expertise and studies indicated that female might lose approximately 13 pounds’ weight which is around 6 KG in the first week after giving birth. The essential point here is that dieting not required for losing the weight, diet often reduce the amount of some important vitamins, minerals and nutrients. **Here are seven tips from the professional nutritionist perspective that can be considered for losing weight after postpartum these are;** 2\. Considered food like fish, chicken, nuts, and beans are excellent sources of protein and nutrients. 3\. A healthy serving of fat, such as avocado, chia seeds or olive oil 4\. With the balance diet please consider to drink plenty of water to stay hydrated. 5\. Regular exercise helps to shed extra pounds and improve overall health. 6\. Fiber-rich foods should be included to promote digestive health and support weight loss efforts. 7\. Don’t forget about self-care. By making these dietary changes and incorporating physical activity, you can achieve postpartum weight loss sustainably and healthily. **Sources:** * Center for Disease and Control and Prevention * Healthy Weight: it’s not dieting, it’s a lifestyle. Obstetrics and Gynecology * The risks of not breastfeeding for mothers and infants. The American College of Obstetrics and Gynecologists * Guidelines of the American College of Obstetricians and Gynecologists for exercise during pregnancy and the postpartum period. Powered by Bundoo®
Charting Your Basal Body Temperature (BBT)
* Charting your basal body temperature (BBT) is a way to understand where you are in your menstrual cycle, helping you to predict the exact point of [ovulation](https://nabtahealth.com/glossary/ovulation/). * Basal body temperature is your body temperature when it is at rest and it increases by around 0.3 – 0.6°C during [ovulation](https://nabtahealth.com/glossary/ovulation/). * Measuring basal body temperature can be done orally, vaginally or rectally and is best taken each morning, after sleep. * Vaginal monitoring is the most precise method with 99% accuracy and can be done using the [OvuSense vaginal thermometer](https://nabtahealth.com/product/cycle-monitoring-with-ovusense/) alongside the [Nabta app.](https://nabtahealth.com/our-platform/nabta-app) A woman’s menstrual cycle lasts from the first day of menstruation to the day before her next period starts. For women who have a very regular 28 day cycle, [ovulation](https://nabtahealth.com/glossary/ovulation/) will usually occur around day 15, which is approximately 2 weeks before the start of the next menstrual cycle. However, a ‘normal’ menstrual cycle can vary from 21 to 40 days, so determining the exact point at which [ovulation](https://nabtahealth.com/glossary/ovulation/) occurs is not that simple. It is, however, possible to use physiological cues (the way the body functions) to determine the likely start of [ovulation](https://nabtahealth.com/glossary/ovulation/); the body produces certain physical signs in response to fluctuating hormone levels and by accurately monitoring these, you may be able to deduce when you are most fertile. Approaches such as [observing cervical mucus](../cervical-discharge-through-the-menstrual-cycle) and measuring Basal Body Temperature (BBT) are types of fertility awareness-based methods that can be used for natural family planning. #### What is Basal Body Temperature? BBT is the temperature of the person at rest. During [ovulation](https://nabtahealth.com/glossary/ovulation/), the BBT usually rises by 0.3 – 0.6°C (0.5 – 1.0°F). By accurately recording the BBT every day, a woman may be able to determine if and when [ovulation](https://nabtahealth.com/glossary/ovulation/) occurred. Typical temperature fluctuations during a normal cycle: * The follicular phase of the cycle is the time before [ovulation](https://nabtahealth.com/glossary/ovulation/). BBT is influenced by [oestrogen](https://nabtahealth.com/glossary/oestrogen/) levels and [progesterone](https://nabtahealth.com/glossary/progesterone/) levels are low. Normal BBT range: 36.4 – 36.8°C (97 – 98°F). * One day before [ovulation](https://nabtahealth.com/glossary/ovulation/) there is a peak in luteinising hormone. BBT reaches its lowest point, known as the nadir. * After [ovulation](https://nabtahealth.com/glossary/ovulation/), [progesterone](https://nabtahealth.com/glossary/progesterone/) levels increase up to 10-fold.Temperature increases 0.3 – 0.6°C (0.5 – 1.0°F) and typically remains above 37°C for the next 10-14 days. This is known as the luteal phase of the cycle. * If fertilisation does not occur, [progesterone](https://nabtahealth.com/glossary/progesterone/) levels and BBT both reduce 1-2 days before menstruation starts. [](https://nabtahealth.com/wp-content/uploads/2019/09/Charting-Your-Basal-Body-Temperature-300x224-1.webp) It is important to always measure BBT in the same way, orally, vaginally, or rectally, using the same thermometer. Measuring under the armpit is not considered to be accurate enough. 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The benefits of tracking your basal body temperature ---------------------------------------------------- Tracking your basal body temperature (BBT) is a simple and effective way to gain insights into your menstrual cycle and fertility. BBT is the lowest body temperature that you experience during a 24-hour period, and it can be measured using a basal body thermometer. By taking your temperature every morning at the same time and recording it, you can create a chart that shows any changes in your BBT throughout your menstrual cycle. **There are several benefits to tracking your BBT, including:** 1. Identifying [ovulation](https://nabtahealth.com/glossary/ovulation/): Your BBT typically rises slightly during [ovulation](https://nabtahealth.com/glossary/ovulation/), which is when an egg is released from the [ovaries](https://nabtahealth.com/glossary/ovaries/) and can be fertilized. By tracking your BBT, you can identify when you are most likely to be ovulating, which can help you plan or avoid pregnancy. 2. Monitoring your menstrual cycle: By charting your BBT over time, you can get a better understanding of your menstrual cycle and how it varies from month to month. This can be helpful for identifying any changes or irregularities in your cycle, which can be a sign of underlying health issues. 3. Assessing your fertility: Your BBT can provide valuable insights into your fertility, and tracking it over time can help you and your doctor assess your overall reproductive health. For example, if your BBT remains consistently high over several cycles, it could indicate that you are not ovulating, which can affect your ability to conceive. 4. Predicting [ovulation](https://nabtahealth.com/glossary/ovulation/): By tracking your BBT and identifying when it rises, you can predict when you are most likely to ovulate and plan accordingly. This can be helpful for those who are trying to conceive or avoid pregnancy. The [Nabta App](https://nabtahealth.com/our-platform/nabta-app/) can be used to record the Basal Body Temperature and store and plot the data. Nabta is reshaping women’s healthcare. We support women with their personal health journeys, from everyday wellbeing to the uniquely female experiences of fertility, pregnancy, and [menopause](https://nabtahealth.com/glossary/menopause/). Get in [touch](/cdn-cgi/l/email-protection#a1d8c0cdcdc0e1cfc0c3d5c0c9c4c0cdd5c98fc2cecc) if you have any questions about this article or any aspect of women’s health. We’re here for you. Don’t forget you can register [here](https://nabtahealth.com/my-account) to become a Nabta member free of charge. **Sources:** * NHS Choices, _NHS_, [https://www.nhs.uk/conditions/contraception/natural-family-planning/](https://www.nhs.uk/conditions/contraception/natural-family-planning/). * “Fertility Awareness-Based Methods of Family Planning.” ACOG, _Women’s Health Care Physicians_, [https://www.acog.org/Patients/FAQs/Fertility-Awareness-Based-Methods-of-Family-Planning](https://www.acog.org/Patients/FAQs/Fertility-Awareness-Based-Methods-of-Family-Planning). * Pallone, S. R., and G. R. Bergus. “Fertility Awareness-Based Methods: Another Option for Family Planning.” _The Journal of the American Board of Family Medicine_, vol. 22, no. 2, 2009, pp. 147–157., doi:10.3122/jabfm.2009.02.080038. * Su, Hsiu-Wei, et al. “Detection of [Ovulation](https://nabtahealth.com/glossary/ovulation/), a Review of Currently Available Methods.” _Bioengineering & Translational Medicine_, vol. 2, no. 3, 16 May 2017, pp. 238–246., doi:10.1002/btm2.10058.