Intermittent fasting has become popular as a weight-loss strategy. But what is it, and how does it compare to continuous calorie-restricted diets?
Fasting for health
Fasting, in general, is not a new idea. Studies suggest benefits for healthy ageing, including regenerating the immune system, increasing Brain-derived Neurotrophic Factor (BDNF) levels in the brain (akin to manure for brain cells!) and improving insulin sensitivity. Animal models also point to the likelihood of reduced toxicity to chemotherapy used for cancer treatment.
The use of intermittent fasting specifically to target weight loss, however, is a relatively new phenomenon with more than 1000 popular books now published and about 40 per cent of UK dieters using a particular approach (eg, the “5:2 Diet”), believing this approach provides superior results compared to less severe daily calorie restriction.
Intermittent vs continuous fasting
Intermittent fasting is where on two days of the week, or every other day, a person eats 70 per cent less than their usual intake. In practice this means consuming up to 500 calories in women or 600 calories in men on the fast days, then resuming a normal diet for the rest of the week.
The effects of intermittent fasting for weight loss have been compared to continuous calorie restriction, where people eat about 25 per cent less calories on a regular daily basis.
Which is best for the waistline?
A limited number of short-term studies show intermittent fasting aids weight loss in overweight/obese people because on the non-fast days they, surprisingly, do not completely compensate for their previously reduced intake. This means their daily caloric intake, on average, is reduced by about 35 per cent. However, their waistline is no better off compared to a daily caloric restriction of similar magnitude, according to the research.
While more studies are needed to assess the long-term consequences of regular fast and feast days, intermittent fasting may be a novel obesity prevention tool in Western countries where weight gain is common with ageing.
Green salad with dill & shallots
An easy and tasty Mediterranean salad that goes with almost any main meal.
Preparation: 8 mins | Cooking: 0 mins | Serves: 4
- 2 baby Cos lettuce hearts (about 230 g), shredded into strips
- 2 shallots (white and green parts), chopped
- ½ bunch fresh dill, chopped
- ¼ cup extra virgin olive oil
- ¼ cup lemon juice
- Wash and spin dry lettuce and prepare as stated. Place in bowl.
- Add prepared shallots and dill.
- Pour over olive oil and lemon juice then toss with tongs and serve immediately. Salad will store, dressed, in the fridge for 24 hours. Pour over dressing just before serving if wanting to store it for a longer period.
You can also use outer leaves from baby Cos lettuce.
PER SERVE: energy 614 kJ (147 cal); protein 1 g; fat 15 g; saturated fat 2 g; cholesterol 0 mg; carbohydrate 2 g; fibre 2 g; calcium 31 mg; iron 0.6 mg; sodium 16 mg.