Do fasting diets really help with weight loss?

    10 June 2019

    Like my stomach, the diet market is expanding rapidly and is twice the size it should be.  This market consists of a series of “lifestyle plans” which gang up on each other by extolling or excluding different food groups.  They abound with acronyms (HFLC, IF, TRE) that refer to increasingly complex plans.  And there’s always a vacuum for older ideas to fill.  Last autumn, a diet from a 1977 issue of Vogue magazine featuring only white wine, eggs and steak went viral on Twitter.  And apparently it works.   I decided to start with Michael Mosley’s new plan, The Fast800, having dropped a stone on his 2013 Fast Diet, which featured the 5:2.  Fast800 uses elements of the 5:2, but asks for a more stringent approach from its hungry consumer.

    For 14 consecutive days you eat 800 calories per day, but only in 8 hours, fasting for the remaining 16 hours each day.  This is known as intermittent fasting (IF).  As well as encouraging rapid weight loss, intermittent fasting has benefits for both body and brain cells.   After about 12 hours of fasting your body runs out of glucose and starts burning its own fat cells, a process known as ketosis.  There is very little new about Mosley’s eating plan.  The recipes are full of low-carb, high-protein meals featuring chicken, lots of vegetables, legumes, nuts and fish. There is very little dairy and only very few grains and other carbohydrates.

    By the end of Day 2 a headache arrived and stayed for a week.  However, I forgot it once I stood on the scales at the beginning of Day 3 and realised I had lost 7lbs.   I knew it was fast, but I hadn’t realised it was going to be so fast that in 48 hours I would drop the weight equivalent to an entire new-born baby.    This is so easy, I thought smugly.  However, the plan instantly stopped working.  I played by the rules for another ten days but lost no weight.  In fact, a new nightmare scenario developed as I put weight back on. How was this possible?   I compared patterns with three fellow Fast800-ers, all women in their early forties.  All of us experienced the ecstasy of rapid weight loss in the first few days followed by ten days in which the diet stalled.

    I discovered that the Mosley Fast 800 was not the only carb-cutting plan which presents problems for women.  Professor Tim Noakes has pioneered a Low Carb High Fat (LCHF) diet called the Real Meal Revolution, on which a sibling of mine has just lost a quarter of his body weight.  Noakes states in his book that although spectacular results are produced in a majority of people “…there are some, more commonly women, in whom the results are less spectacular.” It seems that when faced with a ketogenic diet, the forty-something female hormone system goes on metabolic strike in the last two weeks of its menstrual cycle.  Our fat cells refuse to burn. This is no use on a ketogenic diet.  Still, a rapid reduction in carbs results in an insulin reduction that can mess up oestrogen levels and makes periods heavier, so that’s good. Noakes bans breads, rice, pasta, grains and beans, all fruits except berries, all beans, and those vegetables that have the audacity to grow under the ground.  Peas are particularly deadly.  But he allows hard and soft cheeses, butter and animal fats.

    Noakes’s book is tedious and complex.  There is a chapter at the end full of diagrams of the biochemical features of insulin resistance (Why?  I just want to lose my Malteser tyre, Tim).  From the rugged, charcoal grey font to the manly, meaty dishes, it is clear this is created for middle-aged hunter-gatherer males from the shires.    When you’ve seen one pork belly, you’ve seen them all.  Dry white wine and pure spirits are the only alcohol permitted. So, if your idea of a great night in is to sit with a large block of cheddar cheese washed down with a mug of tepid pure spirits then Noakes is your man.

    After the mildly ketogenic Mosley and the gurning, full-halitosis ketosis of Noakes, it’s comforting to return to something a little more normal.   U.S. News & World Report ranked the Mediterranean Diet No. 1 on its 2019 41 Best Diets Overall list, citing a “host of health benefits, including weight loss, heart and brain health, cancer prevention, and diabetes prevention and control.”  This report ranks diets not just on weight loss but also on overall health.  Ketogenic diets fall significantly further down the list.  The Mediterranean Diet reeks of common sense and decent olive oil, featuring fresh fish, grains, fruit, vegetables and nuts.  Eggs, potatoes and dairy are eaten in moderation; red meat rarely.   It achieves a consistently high score in both short term and long term weight objectives.  You are encouraged to take control of your food by the absence or both portion control and calorie counting. The Mediterranean diet only really works if you take an overall approach; if you only adjust certain elements of your diet but not others, you won’t experience the benefits. It’s simple, effective, scientifically proven and nutritionally sound.  It will not disrupt women’s reproductive systems.  In fact, it reinforces what we have known for over a generation: that the diet of the south Mediterranean remains one of the healthiest on earth.

    So why didn’t I try the most popular peer-reviewed food plan of the last year?

    Because the food plan market had conditioned me to fixate on the rapidity of weight loss.  It is no coincidence that every Michael Mosley book has the word “fast” in its title.  The instant gratification of a large bowl of macaroni cheese had been replaced by the fairly instant thrill of rapid weight loss.  Mosley’s new plan, in particular, is obsessed with the clock.  And when it stopped working I became anxious. The Mediterranean Diet is about slower weight loss and long term health benefits.  If I had adopted a slow plan six years ago instead of Mosley’s Fast 5:2 there’s a statistically bigger chance that I would not be trying to lose the same stone now . In the wake of current fast-loss diet fads, perhaps the laid-back Mediterranean Diet reminds us that the most radical thing we can do as consumers is not to replace traditional foodstuffs with psyllium husks and coconut flour, but simply to eat well, exercise a little patience and slow down.