Lose weight and feel better by eating LESS often
The days of frequent, small meals may be over for some people. Research suggests that our human metabolism is better suited to eating less often. This makes sense because our ancestors would not have had access to food non-stop throughout the day. Three meals plus snacks is a strange artefact of modern living, and it puts considerable stress on our immune system and metabolic hormones.
Intermittent fasting alternates short periods of fasting (14-24 hours) with longer periods of normal calorie intake. Most of the fasting is done overnight during sleep, which is important because that works in concert with our circadian physiology. Sleep is the natural time for the body to detoxify, and to reboot metabolic hormones. In clinical trials, intermittent fasting does improve the sensitivity of metabolic hormones insulin and leptin. (1) Blood tests after fasting show lowered insulin and reduced inflammatory markers. Intermittent fasting reduces inflammation in a way similar to total calorie restriction, but without the calorie restriction (2). Fasting promotes a process of cell clean-up called autophagy, whereby the cell digests pathogens and junk proteins into useful energy.
The restriction of the timing of meals has been shown to improve weight-loss. When mice are restricted to eating within an 8-hour window, they are healthier and less likely to gain weight, even when total calorie intake is high. (3)
Is fasting different for women?
Most of the intermittent fasting studies have been done on men. Women may need a gentler approach, especially women with adrenal fatigue or a history of eating disorder. Women should begin with a short fast (12 hours) and take care to feel well.
Who should do it?
Who should NOT do it?
The method is NOT suitable for pregnant women and children. They should stick with regular small meals. Patients taking insulin should consult their doctor before attempting a fast.
Women with Adrenal fatigue
In order to sustain energy during fasting, the body needs a healthy release of the adrenal hormone cortisol. Those with HPA dysfunction (formerly called adrenal fatigue) may find fasting difficult. They may find that it disrupts sleep. This is a warning sign that fasting may not be appropriate. Women, in particular, may be more vulnerable to HPA dysfunction. Women should fast only on non-stressful, non-work days. They should be sure to include healthy starches (rice or potatoes) with the evening meal before the overnight fast. Carbohydrates calm the nervous system and promote sleep. (For more about HPA axis dysfunction, read Lara's blog post Gentle Carbs and regular eating.)
Those recovering from eating disorder must be very careful with fasting. It can be done. A gentle fast (10 hours) may be helpful to relearn the sensation of genuine hunger and to explore how it feels to satisfy that. It is essential that the fast not be pushed to the point where it triggers bingeing or anorexia.
How to do it:
The method is remarkably versatile. The bottom line is to eat less often.
This could mean restricting to two meals per day - within an 8-hour window. For example, 10am and 6pm meals. Alternatively, some people choose to fast for 24 hours once or twice per week. A small protein or fat snack (such as macadamia nuts or coffee with coconut milk) can be used to ease hunger.
It is acceptable to eat larger meals on non-fasting days. It is not a calorie restricted diet. It is not a starvation diet.
Find it difficult?
During fasting, the body must use fat for fuel. According to Paul Jaminet, author of Perfect Health Diet, intermittent fasting is easier to do if the body is accustomed to using fat for energy. This can be accomplished by the diet to the following proportion nutrient intake (by calorie): 50% saturated and monounsaturated fat; 5% polyunsaturated fat; 30% carbs; 15% protein. Read his fantastic book for more information.
What to expect:
If fasting is correct for you, you should feel well. It should not be a painful ordeal. You should experience improved sleep, and better tolerance to stress. If this is not what you experience, then reconsider what you are doing.
When appropriately done, intermittent fasting promotes detoxification. You should experience an increased appetite for breakfast and better blood sugar control. It can result in weight loss of 0.5 to 1kg per week, particularly around the waist.
1) Halberg, N. Effect of intermittent fasting and refeeding on insulin action in healthy men. J Appl Physiol 99: 2128-2136, 2005.
2) Mattson, MP et al. Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems. The Journal of Nutritional Biochemistry 2005. 16(3): 129-137
3) Hatori M et al. Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet. Cell Metab. 2012 May. PMID: 22608008.