OVERVIEW
· A burgeoning obesity epidemic means that ‘dieting’ has become part and parcel of many people’s daily lives.
· How the mighty have fallen. We dissect the demise of the most popular diet of them all, Atkins.
· Popular diets have one thing in common – they’re all fundamentally flawed.
· We uncover the true effects of dieting and why short-term success turns into long-term failure.
· Finally, we reveal the damaging legacy of dieting on metabolism, which scuppers future attempts at weight loss.
Recent decades have witnessed an unrelenting succession of high-profile fad diets. Each one bursts onto the scene with a flurry of publicity, and an obligatory celebrity endorsement, on its inexorable rise to the top of the bestseller book list. But look beyond the name, the celebrity icon, the pseudo-scientific claptrap, and you’re left with pretty much the same thing – empty promises.
Debate continues to rage over which weight loss diet is best. The ‘high protein, low carb’ movement has been massive, inaugurated by Dr Robert Atkins with the mantle taken up by its less extreme successors, the Zone Diet and the South Beach Diet. Then there are others, fervently claiming the exact opposite to be true, such as the Ornish Diet, which trumpets a ‘low-fat, high-carbohydrate’ mantra. Of course, we have the enduring stalwarts too, such as the perennial Weight Watchers programme, a more middle-of-the-road affair focusing on calorie/point counting rather than specific macronutrient intakes. We could go on… and on… and on…
The diet industry’s claim to fame is that we continue to get fatter. In the USA today, 68% of the population is overweight or obese.
A flawed concept
The truth is that it really doesn’t matter much which dietary approach you choose. Despite new-fangled or pseudo-scientific jargon like the ‘hormone zone’ or ‘ketosis’, they’re all designed to work in exactly the same way – you eating less. While they might promise that you can eat as much as you like, the simple truth is this: ‘the laws of thermodynamics’ aren’t changing any time soon.
A calorie is a calorie and to lose weight you have to burn more energy than you take in, it’s as simple as that!
As we’re about to see, these diets are ultimately founded on a flawed principle. While they can proudly boast an initial weight-loss success, it is short lived. Not only are the effects transient, there’s also a high price to pay. In the long run, there’s a very high probability that the initial hard-earned weight loss will be regained, probably with added interest. And if that wasn’t bad enough, there’s a nasty sting in the tail because, as a result of dieting, you are now likely to gain weight faster and easier than ever before.
Obesity increases the risk of many health problems, such as the metabolic syndrome, type 2 diabetes, hypertension, coronary artery disease, stroke, cancer, reproductive dysfunction, osteoarthritis, and liver and gallbladder disease1.
Low-carbohydrate diets
Without further ado, let’s take this opportunity to drill down and have a look at the daddy of all weight-loss diets, Atkins.
Atkins is the archetypal high-protein, high-fat, low-carb plan. The diet entails eating unrestricted amounts of meat, cheese and eggs, but severely restricting carbs such as sugar, bread, pasta, and even fruit, vegetables and milk. The secret to success (apparently) involves ‘switching our bodies from a carb-burning to a fat-burning machine’. This process is known as ‘ketosis’.
And back in the diet’s heyday, it looked as if Dr Atkins was on to a runaway winner, with astounding results being reported. Testimonials of people losing 6kg or more in a few short weeks were commonplace. Was this just hype? Well, even the scientific trials backed up the impressive anecdotes. In a study of 63 dieters, the Atkins diet was compared to the conventional low-calorie/low-fat/high-carbohydrate diet2. After six months the Atkins proponents were rubbing their hands with glee, it was a whitewash. The Atkins group had lost 7% of their body weight compared to a measly 3.2% in the standard diet group.
But here’s the rub. After one year, the difference between the groups had narrowed dramatically (4.4% versus 2.5%). The initial advantage seen in the Atkins group ebbed away. The reason? The Atkins dieters regained nearly 3% of their body weight. The dramatic initial weight loss was simply a result of depletion of carbohydrate in the body.
Carbs are stored as glycogen in our muscles and liver, along with large amounts of water. Deprive the body of carbs and these stores become depleted. While this makes the numbers go down when you jump on the scales, don’t kid yourself that this is fat loss. Thereafter, any subsequent weight loss is indeed real weight loss, caused by calorie restriction. Yet, despite the fact the Atkins group could eat high-protein or high-fat foods to their hearts’ content, ultimately this still involved consuming less calories, and nothing more magical than that.
This was no one-off. In another study of 132 severely overweight individuals, a low-carb diet caused a far greater weight loss at six months compared with a low-fat diet (5.8kg versus 1.9kg)3, however, at 12 months, these effects were diminished, resulting in little difference between the two diets (now 1.9kg difference)4. The popularity of the Atkins diet duly waned, as people realized its dramatic effects were short-lived, and that once the carbs were reintroduced the numbers on the scale started to move in the wrong direction again. Except for the most ardent dieters, it was simply too much effort for too little reward.
That’s even before we add the potential side effects into the equation. The fact is we really don’t fully understand the biochemical effects of such extreme changes to our diet. Despite gulping down all that saturated fat-laden meat and cheese, the Atkins Diet initially boasted improvements in traditional cardiovascular risk factors, such as cholesterol and triglyceride levels. Great PR for the diet, but surely this was too good to be true? It now appears that these initial conclusions could have been premature and naïve. In studies of mice, despite traditional risk factors not increasing, an Atkins-style diet caused levels of atherosclerosis twice that of a typical Western diet. This was due to dramatic increases in non-esterified fatty acids and decreases in endothelial progenitor cells, which are required to keep blood vessels damage free and healthy5. These are not measured in standard hospital cardiovascular testing, and so the initial clean bill of health for the Atkins dietary regime may be masking a ticking time bomb building up inside our blood vessels.
Other side effects of the diet included constipation, headache, halitosis, muscle cramps and rashes. These, on top of the cardiovascular worries, were enough to put the nail in the Atkins coffin. In 2005, the company filed for bankruptcy protection and, despite reinventing itself as a somewhat more carb-friendly and less-atherogenic version, it remains a shadow of its former self.
By 2004, such was the popularity of the Atkins Diet that it was estimated sales of the book had reached 45 million worldwide4.
We can’t blame the obesity epidemic on our genes. Obesity rates have trebled in a few short decades, which is far too quickly to be blamed on our genes. Obesity is driven mostly by our modern-day ‘obesogenic’ environments.
Short-term gains
Take a cursory look at the evidence on diets and you’ll get the impression that they work pretty well. Let’s take a RCT of 160 participants, evenly distributed to either Atkins (carb-restricted), Zone (high-protein, macronutrient balanced), Weight Watchers (calorie restriction) or Ornish (fat restriction) diets6. After one year, each diet had produced modest weight loss, with participants losing 3.9–6.6kg. (As an aside, we should mention the massive dropout rates – as high as 47% for the Atkins diet and 50% for the Ornish diet – which means if we factor in those participants who didn’t finish the diet, the losses are more like 2–3kg.) Here’s where it gets interesting. Maximum weight loss actually peaked at six months with a 5.2–6.7kg loss and by 12 months subjects had at best maintained, or worse, regained small amounts of weight in all groups. This was most notable in the Atkins group, which regained a whole 2kg (or roughly a third) of the weight loss seen at six months.
Let’s look at a diet offering a so-called ‘balanced solution’, such as Weight Watchers. This programme is based on long-standing medical advice of restricting portion sizes and calorie intake, integrated with a group support system to improve compliance. In a well-conducted, multi-centred RCT of 423 overweight and obese individuals, the Weight Watcher programme resulted in a weight loss of 4.3kg after one year7. But again, here’s the snag. At two years, this had reduced to a weight loss of 2.9kg. The participants had actually gained 1.4kg in weight during the second year of the diet.
These are not a few cherry-picked studies that we’ve selected to prove a point. It’s easy to find short-term studies showing impressive weight loss, but all the long-term studies of dieting show the same thing: after six to 12 months the weight starts to go back on. As it happens, the Weight Watchers study was more successful than most, as the dieters did at least manage to lose a full 3kg in two years. But the sad reality is most long-term studies show that 80–90% of participants return to their starting weight8. All that hard graft and you’re back to square one again.
The annual turnover of the diet industry in the USA and Europe is in excess of a spectacular $150 billion9. It is ironic that the profits of the diet industry grow in parallel with rising levels of obesity. Clearly, the profits of this industry are not performance related!
Long-term costs
So, what’s going on here? The proprietors of the diets would lay the blame firmly at your door. You are weak, you lack willpower and your initial good intentions and motivation, which brought about the early results, waned. They’ll point to that rare success story of miracle weight loss (with obligatory ‘before’ and ‘after’ photos), as evidence of what proper commitment produces. Somewhere along the way you relapsed. Don’t blame them, blame yourself.
We think it’s high time that we placed the blame squarely on their shoulders, and to better understand why, let’s take a look at one of the best-conducted RCTs of dieting that exists. A two-year study investigated various diets with different ratios of macronutrients in 811 individuals (80% of whom actually completed the study, which is impressively high for a diet trial)10. The macronutrients that were emphasized in each respective diet were protein, fat or carbohydrate, but it didn’t make any noteworthy difference and similar weight loss was seen across all groups after two years, with participants losing about 4kg. What is important to note here, however, is that once again most of the weight loss was achieved after six months (on average 6.5kg) and after 12 months all groups started to regain weight. In fact, a mere 23% of participants, less than a quarter, managed to lose weight from month six to month 24.
Let’s drill down to see what’s going on here. At six months the groups were averaging a reduction of 400-plus calories from their starting point, with an intake in the region of 1,500–1,600kcals per day. This intake corresponded to a deficit of about 225kcals per day to lose 6.5kg after six months. At two years the participants were still averaging the 400-plus calorie drop from their starting point and, in fact, their calorie intake was slightly lower, in the region of 1,400–1,550kcals. Yet, surprisingly, this low-calorie intake was now causing participants to regain weight. For these participants, 1,400–1,550kcals now seemed to be a calorie surplus.
Bearing in mind that the recommended daily intake for adults is around 2,000–2,500kcals, the participants were not eating a particularly large amount. However, the damage caused by dieting meant that 1,400–1,550kcals had become their new daily ‘set point’ and if they were now to eat in excess of this pretty miniscule amount, they would gain weight. What was happening?
In 2002, a staggering 231 million Europeans attempted to diet. How many of those do you think were successful in achieving permanent weight loss? The unfortunate answer is less than 1%11.
The body knows best
The truth is that the body isn’t keen on us consuming low amounts of calories over prolonged periods of time. The human body is a primal machine that is highly adapted to getting us through times of food shortage and famine. Deprive the body of energy and it sends a clear message that food is in short supply. This sets in motion a signalling system to preserve our fat stores. It doesn’t stop there either. The body won’t get caught out so easily next time, so to ‘future-proof’ against any subsequent period of deprivation it creates more favourable conditions for energy (fat) storage. This mechanism has actually been known for more than 50 years and has been called the ‘adiposity negative-feedback’ model12.
The body protects itself from food shortage in two ways. First, hormones are released, which act on the brain to increase appetite, thus making it harder to stick to a weight-loss diet. But most important is the second factor, which is called ‘adaptive thermogenesis’. This is where the body dramatically reduces the amount of energy it expends in a 24-hour period. For example, let’s say you lose 10% of your body weight by following a strict diet. This will reduce the amount of energy your body expends by 20–25%8. This reduction is far greater than would be expected simply from the decrease in metabolism from weight loss alone; its effect is over and above that. The upshot? A dieting individual will require around 300–400 fewer calories per day compared to an individual of the same body weight who has never lost weight. If that’s not at least a bit shocking, check this out. These effects may not lessen over time. Dieting for even a few weeks appears to reduce energy expenditure persistently. In fact, these effects have been shown to last for years, with researchers concluding that they are very likely to last indefinitely13.
THE PARTING SHOT
So that’s it. Weight-loss diets might work initially, but for most of us, they will end up making us fatter in the long run. Worse still, any future attempts to lose weight will be harder and more gruelling than ever before. Far from being the antidote to the relentless progression of obesity, en masse dieting is priming us for it. Instead of helping the nation to beat the bulge, the diet industry is fanning the flames.
SUMMARY AND RECOMMENDATIONS
· See ‘fad’ diets for what they are – fads.
· Dieting gives good short-term results, but don’t be fooled as the initial ‘quick win’ is usually short-lived.
· Diets start to backfire after six to 12 months and, despite dieting, the weight starts to creep back on.
· Depriving the body of energy for prolonged periods of time causes primitive mechanisms to kick-in to preserve body fat and ‘protect’ the body from further weight loss, thus making any future attempts at weight loss more difficult than ever before.
· Ultimately, fad diets of any kind aren’t the solution to this oversized problem and in the next two chapters we’ll reveal what does work.