Episode 3: Horizon Special: What’s the Right Diet for You?

This was the third and final episode (shown on Wednesday 14 January 2015 at 9pm on BBC2) and it left a lot of questions unanswered. This documentary is required viewing for all personal trainers in London.

I’m amazed that this is the biggest diet study of its kind in the UK. What have successive governments been doing to reverse the obesity crisis over the last 20 years? Very little, is the answer.

The team of experts included professors on nutrition, genetics, hormones, and behaviour, but conspicuously absent from the team was any expert who specialised in muscle-growth, one of the biggest factors in successful weight-loss.

Lack of “Feel Full” Hormones Cause Obesity?

The programme made much of the notion that hormones are the major reason why some people become overweight. But as the experiments showed, a switch from eating junk food to eating more protein and slow-release complex carbs resolves this.

So the cause of over-eating in this group (the “Feasters”) is not the hormones (which many people use as an excuse to eat as much junk food as they like), but eating the wrong foods.

Even if there are fewer hormonal signals to the brain that you’ve eaten enough, there are plenty of visual signals by looking at how much food is on your plate and controlling your portion size. We’re humans, not lab rats! With much bigger brains than lab rats, we have the ability to decide how much to eat, rather than just react on impulse.

The “obesity hormones” are used as an excuse to eat junk food. There’s nothing more powerful than taking personal responsibility. As a personal trainer in London, I’ve found that clients who decide to take control of their own eating habits and stop blaming their genes, their hormones, their friends and family, are the ones who lose the most weight.

Weight Loss Plateaus

Professor Susan Jebb explained the causes of the “biological backlash”, which is the weight-loss plateau dieters experience when their metabolic rate slows down when they diet. “As you lose weight, your metabolic rate goes down,” she explained, which totally misses the true problem: dieting is self-defeating and doomed to failure.

The reason your metabolism slows to a crawl when you restrict your calorie intake excessively is that the body goes into “starvation mode” and hoards existing fat by lowering your resting metabolic rate, which is the biggest fat-burner. Any weight you do lose is glycogen stores, water, muscle, and a little fat too.

Professor Susan Jebb’s solution to this weight-loss plateau? Eat even fewer calories! This just makes the problem worse. She kept emphasizing how difficult it is to stick to a weight-loss diet. That’s because it’s fundamentally unhealthy to excessively restrict your calorie intake, and all that needless struggle can be so easily be avoided by simply eating healthily and combining it with muscle-building exercise, which raises your resting metabolic rate so you burn fat more effectively.

Eat More Slowly to Lose Weight

One of the better pieces of advice was to eat more slowly. The burger eating experiment showed that one of the “feasters” ate his burger in 2.5 minutes. The experts explained that this was one reason why people become overweight: they eat so fast that the GLP1 hormone (the gut hormone which tells you to stop eating) doesn’t have time to kick in.

Simply by slowing down your eating, by putting your knife & fork down between mouthfuls, eating at a dining table and having conversations with family and friends while you eat (rather than sitting on the sofa watching TV), eating smaller mouthfuls, chewing more thoroughly (these last two were not mentioned in the documentary), you give your hormones a chance to do their job. You feel full before you’ve over-eaten.

Having based the documentary on the notion that hormones are to blame for this group’s weight-gain, they go on to prove that it’s really things like eating the wrong food and eating too fast which are a much bigger cause of weight-gain than any hormone issues.

Exercise and Weight Loss

“Exercise isn’t the best way to lose weight initially” said one of the experts, perpetuating the myth that you need to lose weight by dieting before you start exercising. The combination of exercise and healthy eating is the best way to lose weight, both initially and throughout your life.

The whole focus of the exercise segment of the programme was on calories burned during different activities such as walking, climbing stairs, and comparing it to a vigorous 30 minute exercise-bike session. Not once was there any mention of the most effective exercise for weight loss: resistance exercise to build muscle, which raises your resting metabolic rate and causes the calorie deficit needed to burn excess fat 24 hours a day, not just while you’re exercising.

The programme kept repeating the same mistake: the notion that the calore deficit is best achieved by extreme restriction of calorie intake. Wrong! The healthiest way to create the calorie deficit is to raise your resting metabolic rate by increasing your muscle-mass, which makes your body a fat-burning furnace. Muscle is far more metabolically active than fat.

The more muscle you have, the more effectively you burn fat. Not a single mention of this in any of the three episodes of this fad-diet-obsessed documentary.

Final Weight Loss Results

As a personal trainer, I measure the body fat percentage of my London clients, to monitor their progress. In this documentary, the experts simply weighed the groups to see how much weight they had lost. They didn’t measure how much fat they had lost.

We were told that by then end of the 3 month experiment all three groups combined had lost a grand total of 654kg, an average weight loss of 8% of original body-weight, which exceed the goal of 5% weight-loss.

So clearly a lot of weight had been lost, and much of it would have been fat. However, how much more fat would have been lost by a 4th group which simply ate healthily (no excessive calorie restriction) and engaged in muscle-building workouts? This would be a much more useful experiment.

Strangely, there was absolutely no comparison of the weight-loss results of the different diets the three groups were following throughout the programme. I thought this was the point of the experiment?

Why go to all the trouble of dividing the 75 volunteers into 3 groups according to genes, hormones, and emotional problems, then devise different diets for each group, and then tell us nothing about which group lost the most weight on each diet (let alone changes in body fat percentage)?

Of the three diets, the only one which was healthy was the Fullness Diet given to the “feasters” group with the hormone problems (the other two were fad diets). My guess is that this group lost the most body fat, but it seems we’ll never know.

Dominic Londesborough is a personal trainer in London with over 12 years’ experience.