I have just watched the marathon that was ‘What’s the right diet for you?‘. A Horizon Special on BBC2 that was very interesting for me. Apologies, this is a ‘long read’ 🙂
It was refreshing to see a more scientific basis by which different eating habits were categorised, using some reputable experts called ‘obesity scientists’ although I am not exactly sure why they felt the need to stress the key players were from Oxford and Cambridge Universities?!
So a ‘diet lab’ was set up to conduct a ‘diet experiment’ which involved splitting 75 overweight volunteers into 3 eating types based on the results of genetic, hormonal and psychological testing, allocating them a ‘personalised’ diet that suited them, then tracking their weight loss over 3 months. Their aim was to lose 5% of their body weight – considered to be a tough task. The eating types were
- Emotional eaters
- Constant cravers
Feasters simply can’t stop eating at meal times. This is because they have low levels of a gut hormone called GLP-1 (Glucacon-like peptide 1) so they are less able to register when they are full. To combat this, the group were allocated to a high protein, low GI (Glycaemic Index) diet that helps them feel full for longer. Protein is a good satiator of appetite and low GI foods particularly, (which tend to be rich in fibre) bulk out the gut. Vegetables, beans and pulses take longer to digest and stretch the gut. This sends signals to the brain to tell us we have food in our gut and helps us to feel full. They showed that thick, hearty soups work really well to fill this group up and feel satisfied.
Something else they looked at was the speed at which they ate. Feasters tend to eat quickly and this only adds to the fact they have less GLP-1. By eating much more slowly, they showed their GLP-1 level had a chance to rise to a higher level, helping them to feel more satisfied at the end of a meal, rather than wanting more.
Emotional eaters were those that sought comfort with food. In other words, there are psychological reasons as to why this group overeat. Stress, anxiety, depression or traumatic events increase the release of hormones that promote eating. Therefore this particular group were allocated to weight loss groups (following a low-calorie diet) to ensure they got support throughout their diet. I have to say I didn’t agree with the abseiling down the tower, traumatising the volunteers to test their emotional strength, just to show they would benefit from support. But then again, this was for TV. I was glad however, to see that CBT was also provided (I assume to establish the causes of their emotional eating) in order to help them manage their thoughts, feelings and emotions associated with food.
The programme also suggested that emotional eaters have a stronger, conditioned response around food as a reward. This explains why some people go straight to the biscuit jar when stressed. We have a reward centre in the middle of the brain that, when activated (through feelings of happiness for example), reinforces behaviors. Feeling sad, angry or depressed in this group however, was shown to significantly increase the activity of this area and hence the value of food for these volunteers. For emotional eaters, stress increases the desire for food.
Constant cravers constantly feel hungry AND prefer foods rich in sugar and fat. This was put down to this group’s genes that ultimately gives them a stronger drive to eat, i.e. they are hungrier than most. One of the tests showed this group are much more aware of food around them and even see food differently to others, as if it is an obsession.
The genes to blame here are those that code for leptin; a hormone made by fat cells. The body uses this hormone to monitor fat levels and generally, the more fat we have, the more leptin we produce and the hungrier we feel . As the diets went on, this group found it particularly difficult to continue their weight loss. As they lost weight, their fat stores shrank and so did the amount of leptin they released. This triggered the brain to try and bring the body back to it’s pre-diet weight; to top the fat levels back up again – a self-preservation method really. Signals to the brain become altered so the body thinks it has less leptin than it does, so they felt even hungrier and dieting became harder. Weight loss makes you feel more hungrier so dieting is harder.
One of the initial tests to determine this group involved splitting it in two and sending them strawberry picking after having lunch. Half were given a high protein, low GI meal beforehand and the other half a high GI and low protein meal (basically it was sugary and fatty). I wasn’t sure about this test either. The group that had the high GI meal gave up strawberry picking (one by one) first because they felt hungry. The group on the low GI meal stayed out for much longer as they were not hungry. Now was the first group truly hungry? (I think this is a difficult sensation to be aware of), were they thirsty (as this can be misinterpreted as hunger) or was it because other members of their group gave up so the rest followed suit? Were the low GI group simply more competitive hence they ignored any feelings of hunger just to win? This was not a very robust test in my eyes.
Anyway, this group was then allocated the 5:2 intermittent fasting diet where you fast for 2 days (eating ~500 Calories a day) then eat healthily for the remaining 5. Fasting can be hard for anyone but this group did struggle. On the fasting days this group lost weight as the body had to breakdown fat stores to provide the energy the body needed.
They were also asked to ensure they eat breakfast as one of the tests showed that those who ate breakfast preferred lower calorie foods and had less desire for higher calorie foods. In fact those that skipped breakfast preferred the high calorie foods 40% more and other studies have shown that 75% of successful dieters have breakfast every day
WHAT DID WE LEARN?
This programme certainly starts to explain why there is not a one size fits all when it comes to dieting and the importance of ‘personalised’ nutrition. BUT what the study was trying to show was actually very difficult. If an individual needs tailored advice, they should go and see a registered dietitian or registered nutritionist but applying personalised nutrition to groups doesn’t really work. I liked the advice at the end when Dr. Susan Jebb said don’t look at the fad, celebrity endorsed diets, look at yourself and your own eating habits and relationship with food. This is very true but on the other hand are we sufficiently self aware or have access to these genetic and hormonal tests to tell us what type of eater we really are.
You can do the quick and easy test yourself via the BBC website here
The other issue, having just done the test on myself is what do you do if you come out in multiple groups? I wonder if many other people have found this? I am 68% constant craver and 32% feaster so in theory if I needed to lose weight, how do I decide what diet is best? Do the 5:2 diet AND make sure I have low GI and high protein? I do think about food a lot but that’s because I love it and because I am a bit of an organisational freak and like to plan meals ahead of time. I don’t think this makes be a constant craver. Or maybe it does but I have a good amount of restraint? This certainly wasn’t what I expected so I am not sure how sensitive the test is (there are only 12 questions too).
Either way, the results for these volunteers on the programme were really positive. In part, their success could have been driven by the fact they were almost told the diets would work for them. To discover there may be REAL reasons why they have struggled with their weight all their lives, that it is not because they have failed X, Y and Z diet and it is not their fault, will drive and motivate them again. You could almost see the relief when realising this and how empowered they became.
WHAT CAN YOU TAKE HOME FROM THIS?
There were a number of take home messages suitable for everyone from this programme which I thought were really helpful:
1. Initial weight loss is always going to be quite significant, before slowing down after the first week and then possibly levelling out completely. This is normal as we lose mostly water to start with. This is when the honeymoon period is over and we need real energy and effort to maintain those healthier eating habits. This is when we need to plan, plan, plan and ensure we get enough sleep to make good food choices (particularly if you are an emotional eater).
By week 4 the plateau really kicked in. This happens because our new healthy eating habits are not yet established but also the body tries to slow down the rate of weight loss. As a result, our metabolic rate (the rate at which we burn Calories) slows down as we lose weight (by ~5%) so we will need less food.
2. Once you have started to get to grips with your dietary changes, exercise will be very important to help boost / maintain your metabolism and hence the ability to lose weight. Everyday activities of living were shown to be hugely effective at increasing the daily Calorie burn (equivalent to a 4hr run over the course of a week!) Use a pedometer to provide constant feedback about reaching your activity target. Try these:
- Stand up whilst talking on the phone
- Walk instead of taking public transport
- Take the stairs not the lift
- Carry your shopping instead of using a trolley (when possible!)
3. Don’t go shopping when you are tired or hungry but more importantly, make a list before you go. Choose a time when you feel fresh – in the morning or the night before to help ensure you make the right choices and make fewer impulse buys. In the programme they showed shoppers that were tired chose foods that contained more sugar, saturated fat, and nearly double the number of calories!
4. Slow down your eating to help your body register when it is full (and get more GLP-1 released) Try these:
- Sit down
- Take sips between mouthfuls of food
- Put the knife and fork back down between bites
- Cut food up into small pieces
5. If you fall off the wagon, don’t beat yourself up about it. The programme talked about Catastrophic thinking – when you give up and lose all restraint when you fall off / have that huge piece of cake. Rather than think what the heck, get straight back on the wagon again and refocus.
6. I think a low GI diet would be beneficial for most, not just feasters. We know how a diet rich in fruit, veg and whole grains confers a number of health benefits including appetite control and weight management. Thick hearty vegetable based soups can make a really satisfying lunch.
7. Always eat breakfast. Interestingly some research has emerged that may question this statement. A few studies found that not eating breakfast made no difference to weight loss. However, when you look at the other benefits that breakfast provides (I’ll be writing about this in another week or so for ‘Breakfast Week’) like providing important nutrients, increasing alertness, ability to concentrate, improving mood (which can certainly affect what you eat) and reducing the risk of disease, why wouldn’t you?!
I would also add that everyone needs support – not just the emotional eater. By all means, join a weight loss group but if this is not your cup of tea, try to find a buddy that has similar goals and will help you along your journey.