THE SCIENCE OF WEIGHT LOSS
Why do I find it difficult to lose weight?
Hey, this is normal! Let’s start with some truths.
- ‘Healthy eating choices’ is nothing but a sound bite. We don’t chose to be overweight. Automatic actions are wired into our brain. Conscious choices require effort that is simply not sustainable 100% of the time.
- High calories Foods surround us. Just look at the ‘Supermarket Specials’ with their discounts for large quantities. Increased weight can feel like a battle where the ‘two sides’ are the brain-gut interface, and the ‘obesogenic environment.’
- The environment requires less physical activity than than in the past. Cars, lifts & gadgets reduce the need for us to be moving.
Genes play an important role in a whole host of different factors – our metabolic rate, how much we fidget, how much energy we use to control our posture, and how we respond to different diets. Our genes have evolved to prevent weight loss, not to prevent weight gain.
Hormones play a key role in regulating metabolism and hunger. These hormones act like a thermostat – except that we have little control over the setting. In this way, the body ‘remembers’ what its Basal metabolic rate ‘should be.’ This ‘metabolic memory’ may even start before we are born, and explains why our body wants to ‘be’ at a certain weight.
Let’s get into the science.
How our body ‘wants’ us to regain the weight we have lost
Weight loss Science isn’t Sexy but it is empowering.
The metabolic rate of people who have lost a lot of weight is around 500 calories lower than their baseline – even many years later.
The metabolic rate drops around 100-200 calories more than is explained by the lower body weight. Why is this?
Fat cells send the hormone ‘Leptin’ to the brain. Leptin increases energy expenditure. Weight Loss results in lower leptin levels which reduces our metabolic rate. Ouch.
Let’s check out the really important gut hormones that also send messages to the hypothalamus in the gase of the brain:
- Ghrelin – produced by the stomach and makes us feel hungry. Levels increase after weight loss.
- CCK, Peptide YY, GLP-1, PP, insulin – these hormones make us feel full. Levels reduce after weight loss. Leptin also goes down after weight loss.
Weight loss through diets will lower your metabolic rate and increase your drive to eat.
Weight and Our Brain
Cravings are the elephant in the room when it comes to weight loss. Food cravings are a ‘conditioned response’ to a situation. Chocolate is the most common craving. If you always eat chocolate when you watch a movie then your cravings will increase when you put on a flick. Perhaps you crave a snack in the middle of the afternoon? The trigger for mid-afternoon cravings is usually work.
Try to identify your triggers for ‘automatic eating’ – perhaps fatigue, bordeom, or stress. You can then put in some strategies to over-ride our instinctive behaviours.
What happens if you try to resist a craving and eventually give in to it? You’ll feel a sense of failure that in turn increases the cravings! Don’t beat yourself up if you ‘give in’ to your cravings sometimes. Overall, however, you should simply try to cut out that food that you crave for. Use mindfulness techniques & try to ride the wave of the craving. Cravings do go within around 30 minutes. A useful rule of thumb is that it takes around two months of conscious effort for the cravings to pretty much disappear. Keep your partner on board and tell him or her not to buy you that food again!
There are important Psychological issues that affect us all:
- We tend to make choices that sort out the current situation (relieve of hunger) than help the long term issues (our weight).
- We all tend to make the same choices we’ve made in the past: the so-called status quo bias. Make consistently different choices than we’ve made in the past takes gets easier with time
Long term weight loss is possible. It helps, though, to be aware of the multiple factors that make sustained weight loss so challenging – so that you can develop helpful long term strategies and make informed choices.
The end result is that weight is like an elastic band. Efforts to reduce weight are often very difficult to maintain over time so that the weight springs back up (again).
What should be my target weight?
- Aim for sustained weight loss. The health benefits of a 5 to 10% loss of weight are considerable.
- Set a realistic goal eg. 5 to 10% weight loss.
- Aim for a reduction of 0.5 to 1Kg per week.
Major Medical Guidelines regard a 5% weight loss as successful.
Many clients will lose, say, 15Kg or more but the priority is to keep the weight off.
There is no doubt at all that weight reduction methods have to be sustained over many years.
What non-medical options are there?
Most clients have tried to lose weight many times. Each time you regain weight you reinforce the notion that you are a failure. This is simply not correct but you are up against hundreds of millions of years of evolution.
The main non-medical options (which may be combined) include:
- Regular physical activity – of course very important but not enough on its own. Physical activity is very important to stop weight regain.
- Diets – lots will make promises, research doesn’t come down heavily on one being better than another. Consider, however, the proven health benefits from eating a Mediterranean-type diet.
- The very low energy diet is described later on.
The occasional client sustains very significant weight loss with a particular type of diet. These experiences are not reproducible. In other words, what works for one person may not work for another.
It’s important for people to feel supported in their attempts to lose weight through physical activity and dietary changes.
Any dietary tips for weight loss?
The truth is that no particular diet program is superior to another for weight loss or weight maintenance. Evidence from scientific studies support the following:
- Look at portions & proportions. Some people prefer to leave their plate empty even if they are already full.
- Use a smaller plate size. Studies show that the same amount on a smaller plate looks bigger.
- Consider increasing the proportion of vegetables relative to grain & protein foods.
- Cut out Sugary Drinks – evidence from three trials shows that this change results significant weight loss
- Drink 500mls of water half an hour before a meal has been proven to help with weight loss.³
- Be aware that fruit drinks usually contain a high amount of calories.
Extreme diets such as liver detox and juicing have minimal to no scientific evidence. Having said that, do whatever you need to do to restrict calories in a sustainable healthy way.
What is a Very Low Energy Diet?
A Very low energy diet (VLED) is a diet with less than 800 kCal per day. Optifast is the best known in Australia and is provided in a “kit form” – as shakes and soups for example. The first phase lasts up to 12 weeks and typically includes 3 meal replacements per day, at least 2 low-starch vegetables, 1 tablespoon of oil, and 2L of water.
A VLED works because it induces a state of “ketosis” that in itself reduces appetite. After a few days, the chances are you won’t feel hungry although there may be side effects such as fatigue, dizziness & menstrual disturbances.
Evidence shows that a VLED leads to a substantial weight loss when supported & monitored by both The GP & dietician.
The big advantage of a VLED compared to a normal ‘diet’ is that the ketosis suppresses appetite. Why? Because ketosis causes an increase in cholecystokinin which is a natural appetite suppressant. Ketosis also suppresses the hunger-hormone ‘ghrelin.’ In effect, ketosis is your friend.
The clinic has its own VLED recipe which is not quite as intense as the 100% VLED whilst still being effective.
A Very low energy diet (VLED) is not suitable during pregnancy, breast feeding, adolescence, age over 65, recent heart attack & some rare medical conditions such as porphyria. Also avoid with alcohol or drug abuse. May not be suitable in people with specific psychological problems.
The doctor will check your medical history, perform an appropriate physicam exam including your Blood Pressure, and arrange an ECG & Urine Test when appropriate. Guidelines suggest baseline blood tests that are repeated should the diet continue at 3 months.
What medication is available to help weight loss?
Specific medical treatments may supplement lifestyle attempts to loose weight and there are a range of options.
Note that we describe medication class rather than brand names as per google guidelines.
CNS Stimulant: This is the best known class of appedite suppressants that work by increasing the available dopamine in the nervous system. Side effects include palpitations and headache. Some doctors are very conservative and restrict the course to 3 months. The evidence points towards a weight loss immediately following treatment of around 3.5Kg.
Antiepileptics are not licensed for weight loss on their own in Australia. Side Effects are dose-related. The combination of an antiepileptic and appetite suppressant is available in a single tablet in The USA and is available in Australia as a compounded medication.
Medication usually used for Diabetes has been around a long time to treat type 2 diabetes and more recently polcystic ovarian syndrome (PCOS). A study of women with infertility & excess weight showed a loss of BMI of 0.68 after 6 months, and another study of women with excess weight on anti-psychotic medication² found a weight loss of 4.8% after 3 months.
Lipase inhibitors: reduces absorption of fat from the gastrointestinal tract. Dietary fat in the gut is therefore not completely broken down – and so remains in the bowel – and ends up in bowel motions. So the classic side effects are oily spotting of the bowel motions, flatulence, loose stools – these are most noticeable after a fatty meal. The evidence points to a weight loss of around 3Kg weight loss at 1 year’s treatment.
Glucagon-like Peptide agonist for weight management was introduced in Australia in 2016. The cost is a big factor for most people at around $387 per month. The injection is self-administered daily via an injection pen. The results from the clinical trials look encouraging with 1 out of 3 people losing over 10% of their body weight.
Serotonin 2C receptor agonist is available in the USA but not in Autralia yet, and is a specific anti-obesity medication that results in a 3.2Kg average weight loss.
What about Bariatric Surgery?
Bariatric surgery often results in sustained significant weight loss. There are over 5 Bariatric Surgeons in Brisbane. Out-of-Pocket costs of a gastric sleeve after insurance varies significantly. Typically, the out-of-pocket cost is around the $2500 to $3500 mark in Brisbane though there are some services a little further away that get this down to around the $1500 mark.
The barrier to bariatric surgery are:
- Concerns over side effects
- Cost. Some medical insurance companies do not cover bariatric surgery but plenty do – including the option to be covered immediately on joining (ask!).
- Perhaps a feeling that obesity can be “beaten” without surgery – maybe it can & certainly other options should be pursued.
Weight loss statistics (in general) are not encouraging. A 10 year follow up study of nearly 280,000 people showed “The annual chance of obese patients achieving five per cent weight loss was 1 in 12 for men and 1 in 10 for women. For those people who achieved five per cent weight loss, 53 per cent regained this weight within two years and 78 percent had regained the weight within five years.” However, within these figures some people do manage to maintain weight loss.
There has been quite a lot of publicity over side effects of bariatric surgery. When considering risks, bear in mind also the risk of ongoing severe obesity. The risks of ongoing obesity are usually the back of people’s minds when bariatic surgery is suggested.
The UK NICE guideline on bariatric surgery were updated in 2014 to suggest bariatric surgery be considered for people with
- BMI 40 or more
- BMI 35 or more with type 2 diabetes or high blood pressure or other significant conditions
Consider this: The NICE guidelines are funded by the UK government to advice on what the publicly funded national health service should fund in the UK – at a time of major resource limitations. The NICE guidelines suggest bariatric surgery at these thresholds because they have assessed the scientific facts: The risk of ongoing moderate to severe obesity generally outweighs the risk of surgery. This message may be lost at times because the risks of obesity is not something that is “out there” as much as it should be – perhaps because of the sensitivities involved. The Risks of being overweight are wide-ranging.
Without surgery, around 90% of people with obesity eventually regain the weight they’ve lost. The author of this blog is a strong advocate of weight loss surgery.
The risk of ongoing moderate to severe obesity generally outweighs the risk of surgery
What are the health benefits of weight loss?
How do you feel when you stand on the scales waiting for the tiny movements to settle down? A client who loses 15-20Kg does not require a list of medical reasons to lose weight, they just feel better.
The health benefits of weight reduction include:
- Reducing or controlling diabetes
- Reducing cardiovascular risks
- Improving high Blood pressure & Sleep Apnoea
- Weight Loss also helps Polycystic Ovarian Syndrome and improves fertility rates following IVF.
The cancer risks of a high BMI are perhaps less well known. The lancet published a study into the effects of obesity on 22 different cancer and found that obesity is linked to 17 of them. Some of these links between weight and cancer are strong associations.
1: Li Z, Maglione M, Ti W, et al. Meta-analysis: pharmacologic treatment of obesity. Ann Intern Med 2005;142:532–46.Women of reproductive age
2: Nieuwenhuis-Ruifrok AE, Kuchenbecker WK, Hoek A, Middleton P, Norman RJ. Insulin sensitizing drugs for weight loss in women of reproductive age who are overweight or obese: systematic review & metanalysis.
e3 Hlen M. Parretti et al, Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT; obesity, 2015