Intermittent fasting is a popular dietary approach that involves cycling between periods of fasting and eating. In this blog, we will explore the science behind intermittent fasting, how it works in practice, potential side effects, and provide tips on what to eat and what to avoid.
Understanding Intermittent Fasting
Intermittent fasting can be done in two main ways: the 5-2 diet or the 16-8 diet. The 5-2 diet involves eating normally for five days a week and consuming around 500 to 600 calories on the remaining two days. On the other hand, the 16-8 diet restricts eating to an eight-hour window and fasting for the remaining 16 hours of the day.
The science behind intermittent fasting lies in its ability to utilize stored energy, particularly excess body fat, resulting in weight loss. When we consume more energy from food than our body can immediately use, the hormone insulin is produced to break down carbohydrates into glucose. Glucose can either be used by cells for energy or stored as glycogen in the liver and muscles. When the body needs a quick source of energy or isn’t receiving glucose from food, glycogen is released and broken down into glucose.
However, there is limited storage space for glycogen, and once the stores are full, the liver converts excess glucose into fat. When we fast, insulin levels decrease, signaling the body to start burning stored energy. One of the primary energy sources used during fasting is glycogen. Once the glycogen stores are depleted, the body starts breaking down fat for energy, resulting in weight loss.
The Methods of Intermittent Fasting
The two most well-known methods of intermittent fasting are the 5-2 diet and time-restricted eating. The 5-2 diet involves eating normally for five days and reducing calorie intake to 500-600 calories on the other two days. Time-restricted eating, on the other hand, follows a 16-8 cycle, where eating is restricted to an eight-hour window, with 16 hours of fasting each day.
Foods to Incorporate
When not fasting, it is important to maintain a healthy diet aligned with general health eating guidelines. Here are five food groups to consider incorporating into your diet:
- Whole grains: Oats, whole grain bread, whole grain pasta, and brown rice provide slow-release glucose, fiber, vitamins, and minerals.
- Lean meats and fish: Skinless chicken, low-fat turkey, white fish (haddock, cod), and oily fish (salmon, sardines, tuna, mackerel) are excellent sources of protein and omega-3 fatty acids.
- Dairy products: Choose low-fat varieties of dairy products, such as skimmed milk and low-fat Greek yogurt, to benefit from their calcium content, essential for bone health.
- Fruits and vegetables: These provide essential vitamins, minerals, and fiber necessary for overall health.
- Lentils, beans, and pulses: They are low in fat and rich in protein, fiber, vitamins, and minerals.
Foods to Avoid
While following an intermittent fasting diet, it is advisable to avoid certain foods:
- Refined carbohydrates: White flour, white bread, white rice, white pasta, and many breakfast cereals cause rapid spikes in blood glucose levels.
- Sugar: Simple sugars like table sugar, maple syrup, and foods with added sugar such as sugary drinks, sweets, chocolates, ice cream, and biscuits.
- Complex animal fats: Dripping and lard, high in saturated fat, should be avoided on a low-fat diet.
- Red or processed meat: Bacon and sausages, high in saturated fats, should be limited. Opt for lean meats or remove visible fats when consuming meat.
- Processed foods: Cakes, pastries, biscuits, pies, and convenience foods are usually high in calories due to the amount of saturated fat and added sugar they contain.
Possible Side Effects
Some individuals may experience headaches and constipation when starting an intermittent fasting diet. These risks can be minimized by staying hydrated, consuming plenty of fluids, and incorporating a variety of fruits and vegetables into your meals.
Conclusion
Intermittent fasting can be an effective method for weight loss, but it is essential to consider your own health and medical conditions before starting any diet. If you have any concerns or questions, it is recommended to consult with a trained and registered dietitian or your healthcare provider for personalized advice.
