Over the past few years, you’ve no doubt had your social media feed cluttered with fit-fluencers, health seekers and celebrity nutritionists flaunting the benefits of fasting diets.
But are they as great as everybody seems to claim, what are the options, and do they work?
While there is a huge variety of fasting diets, from the 5:2 to the 16:8, they’re all based on the same principle: reducing the amount of kilojoules you consume over the long-term.
Intermittent fasting: how it works
Our bodies have evolved to allow us to survive when food is scarce (thanks, ancient ancestors), meaning we’re able to survive for a short time on a greatly reduced food intake.
In the modern world, this is rare, but the principle of short-term survival without food is the basis for intermittent fasting.
In a nutshell, intermittent fasting is a term to describe restricting your kilojoule intake by varying mealtimes, alternating periods of fasting with periods of eating. Like any diet, the aim is to consume less food energy than the amount you burn through activity during the day.
Normally, when we eat food it’s broken down into molecules. For instance, carbohydrates (sugars and refined grains) break down into glucose, which is converted by our cells to be used for energy.
Intermittent fasting aims to increase weight loss by lowering insulin levels. With lower insulin levels, our cells release stored sugar and burn it as energy.
Our cells need insulin to store energy in our fat cells, so the intermittent fasting theory is that when insulin levels drop, our cells release the stored energy and burn it, thereby burning those extra unwanted kilos.Intermittent fasting may help you maintain a healthy weight by reducing your energy intake #health #fasting Click To Tweet
Types of fasting
You’ve probably heard of a whole range of intermittent fasting regimes. Essentially, they’re just different ways of dividing up the day and week into fasting and not-fasting periods.
Some common fasting diets include:
Alternate-day fasting: Fasting every second day, reducing your kilojoule intake over the week.
The 5:2 diet: This type of intermittent fasting became popular after UK doctor and journalist Michael Mosley wrote about trying the diet and subsequently published his book The Fast Diet. The guide is to eat normally for five days of the week, while eating less kilojoules on the other two days.
The 16:8 diet: Eating during an 8-hour window during the day and fasting for the remaining 16. For instance, having dinner at 6pm and then not eating breakfast until 10am the next day.
The 20:4 diet: A more restrictive diet, where you eat only for four hours each day.
Fasting animals live longer
Fasting in some form has been practiced for centuries by different religions and cultures. The first medical studies into its benefits were even done as early as 1915.
Since then, there have been a lot of studies into the effects of fasting on rodents, fruit flies and roundworms, finding that those animals that ate a third less kilojoules than the control group lived longer lives.
Some studies found that rats put on fasting diets lived longer than the rats who ate whenever they wanted. Other studies also found the rats had lower levels of insulin and glucose in their blood. We’ll explain why that matters in the next section.
Once studies in animals started showing they lived longer, fasting diets became increasingly popular as a method for humans to lose and manage weight.
Of course, while we’re not rodents, fruit flies or roundworms, the benefits for humans have been vast and varied.
Potential benefits of fasting
While some people swear by fasting diets as a way to manage their weight, it’s important to note that fasting doesn’t suit everyone. You should always speak with your doctor before dramatically changing your diet, especially if you are living with a chronic health condition.
A review by the New England Journal of Medicine in 2019 found that fasting for 18 hours a day may trigger a metabolic switch from glucose-based to ketone-based energy, leading to increased stress resistance and longevity, and a lower rate of diseases such as cancer and obesity. Some of the effects of fasting may also include:
- Weight loss by reducing kilojoule intake
- Lowering insulin levels
- Boosting levels of growth hormone
- Increasing the release of the fat burning hormone norepinephrine
Possible risks of fasting diets
Dramatically cutting your energy intake can have other, less positive effects on your body, especially if done over a long period. That’s why it’s important before starting a fasting regime to understand the potential risks against benefits, to determine if it’s right for you.
In the short term, intermittent fasting can cause low blood sugar, headaches, dizziness, and fatigue. Long-term fasting can lead to problems such as muscle loss, anaemia, and vitamin and mineral deficiencies.
It’s a good idea to speak to your doctor before trying intermittent fasting, especially if you are living with a chronic health condition such as diabetes or heart disease, or if you are elderly or pregnant.If you have a chronic health condition, are elderly or pregnant, see your doctor before dramatically changing your diet #fasting #health Click To Tweet
Fasting diets: not the only option
While there is good evidence for the effectiveness of certain fasting diets if they are done as part of a healthy lifestyle, they’re not the only option to achieving and maintaining a healthy weight.
A plant-rich diet that you can follow for the long term, complemented with regular exercise, is also an effective weight management option. A balanced diet should include lots of vegetables, fruit, whole grains, lean protein, dairy and healthy fats.
Your doctor or dietitian will be a great support in helping you map a plan that is right for your body, and in line with your weight loss and health goals – for either a fasting diet, or an alternative approach.
And if you’d like to keep track of your health at home while modifying your diet or aiming to achieve a healthy weight, our at-home thyroid and diabetes tests are an easy way of keeping track of those conditions in between visits to your doctor.For optimal health, follow a healthy, plant-based diet and get lots of exercise #health #diet #nutrition Click To Tweet
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