Understanding over eating, exercise and obesity


This blog provides free general information for anyone who is seeking to understand the causes of obesity in our society, not intended as a medical consult. Please seek proper dietician or nutritionist advice for individual assessment and management.


The crucial learning points are:

  • Reasons for obesity (food portion, food choices, eating habits and physical exercise)
  • The different weight loss diets that are available
  • Medications use for weight loss
  • Key elements to lose weight
  • How to successfully maintain weight loss




Reasons for obesity

In Western society we are accustomed to large meal portions. If possible think of your trip to a third world or perhaps an Asian country, when you are served a small bowl or plate for lunch. Your first reaction may be that the serving size is way too small.

In contrast think of your trip to North America, having ordered exactly the same food for lunch, only to find out that the serves are much bigger than what you may be accustomed to. Your reaction may be that this super size meal is enough to feed you for the whole day!

Similarly in Australia we have problems with large food portions and second helpings. On top of that the food we consume are relatively low in nutrition value but calorie dense, often consist of preserved, highly processed, refined type foods instead of fresh fruits, vegetables or meat that previous generations are more used to having. Food served in restaurants are extremely tasty but at the same time they do contain a high level of salt, sugar, spice, sauces, various condiments, oils and dressings. Indeed a success of modern Australian meals with fusion of other cultures and it is a great blessing having an abundance of food to enjoy.

In our modern society, the job demands, shift work and busy lifestyle filled with family and social events, often dictates the irregular meal times and the speed of how we consume our food. Lunch can be consumed in less than 10 minutes and leave us unsatisfed with the persistent hungry feeling. This may lead to compulsive or binge eating behaviour (see below).

These three factors above coupled with a relatively more sedentary lifestyle are the main reasons for the rapid rise in the prevalence of obesity, type 2 diabetes and various associated medical problems in Australia.

Listed below are some examples of poor food choices almost everyone (myself especially) are guilty of. Making mention of it improve awareness and help facilitate change, one step at a time.


Types of food

For some people the major proportion of their diet consist of either comfort or convenience food. Comfort or indulgence food (eg. chocolates, ice cream) are eaten to relieve stress or a negative emotion. Convenience food or tertiary processed food require minimal cooking and are sold for commercial profits.

Examples of convenience food are preserved or processed meats, sweets/lollies, high calorie beverages, chips, etc. that are often high in saturated fats, salt and sugar, all of which may be high in flavour but low in nutritional value. Included in this category are fast foods (eg. pizza, fried fish and chips, kebabs, Chinese take away, doughnuts, etc.) again very high in calories.


Western diets often have a high saturated fats and cholesterol content, high sugar content (in the drinks or desserts) and have refined grains.We have a preference for more carbohydrate and fats, less protein, fresh fruits and vegetables in our diet mix.

High calorie diets or drinks will counter any attempts of weight loss if the consumer is not aware. This group of food includes nuts and seeds, alcohol, cheese, pasta, rice, potatoes, bread, avocado, coconuts as well as the usual animal fats, vegetable oils, salad dressings, peanut butter and sweet desserts.

Instead of the above most of us should have preferences for fresh fruits, green leafy vegetables, fresh unsweetened juice, whole grain, whole meal or meat without the skin/fat. Please refer to a food pyramid.



Eating habits

Some of the common undesirable eatings habits are listed below.


Compulsive over eating describes consuming large portions of food during meal time that may be followed by a sense of guilt or loss of control.

  • A loss of dietary restraint (disinhibition) which are often initially triggered by a hunger sensation or an emotional event (comfort eating).


Grazing or nibbling describes consuming smaller meal portions frequently even when not feeling hungry.

  • Snacking or small portions of food consumed continuously are often triggered by inactivity or loneliness and inevitably result in progressive weight gain over extended periods of time.



Hedonic hunger describes the desire to eat highly palatable food, food high in saturated animal fats and sweets (especially chocolates, cake, cookies, chips) which reflects poor food choices high in calories, often conditioned by experiences whilst growing up and living in an affluent Western society.


Binge eating disorders describe a behavioural disorder that may include difficulty in controlling the amount of food being consumed, eating when feeling bored, eating continually (no planned meal times), when not hungry or eating too quickly.


Good eating behabiour thus consist of good food choices (refer to a food pyramid), in correct food portions  and maintaining good eating habits. Also after bariatric surgery, adequate daily protein intake is highly recommended mainly because protein helps maintain satiety and preserve lean body muscle mass, which in turn enhance further weight loss, helps with body contour and prevent long term weight re-gain.



Physical inactivity

Needless to say modern day conveniences has improved living standards dramatically and we are reliant upon modern technology to function. It is only unhealthy when we live a solely sedentary existence and does no exercise. Sedentary lifestyle describes minimal or lack of any physical activity performed at work or at home and for many obese patients at least 80% of the day is sedentary.

Unfortunately in Western societies it is the sedentary lifestyle coupled with poor eating habits, poor food choices in large amounts (eg. eating chips or popcorn whilst watching television for prolonged periods of time) that is responsible for the reduced energy expenditure and higher than ever prevalence of obesity, type 2 diabetes, cardio-vascular disease and many other related co-morbidities.





Weight loss diets


There are almost endless recommendations and various diet trends that are introduced into our society from time to time, successfully marketed and sold commercially. Instead of deciding which one is the best, it is easier to understand which category that particular diet belong to. Listed below are some examples:


  • Low fat diets are usually recommended for patients with type 2 diabetes at risk of coronary artery disease
  • Energy deficit diets involve calculating an individual’s daily energy requirement and recommending a diet that result in energy deficit of ~600kcal/day to induce weight loss of ~0.5kg/week
  • Meal replacement diets are commercial products (shakes, bars, soups, etc.) that replace 2 meals a day and allow 1 regular healthy meal, gives an estimated caloric intake of 1200-1600kcal/day
  • Very low calorie diet (VLCD) are commercial products (eg. Optifast) that provides 450-800kcal/day to replace all meals and snacks, this will induce rapid weight loss and are usually recommended for 2-3 weeks leading up to bariatric surgery
  • Low glycemic index (low GI) foods have less simple sugars or carbohydrate which is recommended to reduce hunger, increased satiety, decrease insulin resistance, reduce cholesterol and to prevent early dumping syndrome
  • High protein low carbohydrate (eg. Atkins’ diet) have reduced carbohydrate (calorie) content to help reduce calorie intake but they may have adverse side effects
  • High protein low fat (eg. CSIRO diet) allow eating satisfactory/enjoyable meals in smaller quantities (eg. trimmed red meat) to assist with body fat loss and preserve lean body mass with beneficial effects on diabetes and heart disease


It is common to recommend VLCD especially in the 2 weeks leading up to bariatric surgery in order to make the operation technically easier by reducing the size of the fatty liver and mass of the internal visceral fat. Hence weight loss commences in the period leading up to surgery.

After bariatric surgery the patient will remain on fluids and soft pureed diet for a period of time (usually between 2-4 weeks) before returning to solid meals. The VLCD diet helps patient to make a smoother transition after the surgery whilst they are learning a new eating habit and more importantly providing the necessary daily protein replacement, vitamins and trace minerals.



Medications for weight loss
The information below is from available from MIMS Australia.


Phentermine (Duromine or Metermine)

This is an appetite suppressant that works through the central nervous system (hypothalamus).

This is prescribed only for short duration (usually less than 3 months).  It will also affect the dopaminergic and noradrenergic nervous system resulting in serious side effects on the heart (rapid heart rate, palpitations, elevated blood pressure, chest pain) and dangerous drug (MAOI) interactions may result in hypertensive crisis.


Important to note is that this medication should not be prescribed to patients with cardio-vascular diseases (systemic hypertension, heart valve disease, pulmonary hypertension, previous strokes), psychiatric illness or patients on monoamine oxidase inhibitor (MAOI) or selective serotonin re-uptake inhibitor (SSRI) medications or thyroid diseases


Some of the drug adverse reactions may include angina, myocardial infarct, stroke, insomnia, irritable, nervous-agitated state, nausea, vomiting and abdominal cramps.


Orlistat (Xenical)
This is a gastro-intestinal (luminal) lipase enzyme inhibitor to reduce absorption of dietary triglycerides (to prevent the breakdown to triglyceride to monoglyceride and free fatty acids), helps to reduce absorption of dietary fats by up to 30%. Needless to say it is recommended for patients who has a high animal fat content in their diet, not for those with preferences for sweets or starch.

This drug is minimally absorbed and has no systemic lipase inhibitor effect. The desired effect is not just for weight reduction but for lowering of total and LDL cholesterol as well.


The medication should not be prescribed to patients with exocrine pancreatic insufficiencies or those with major intestinal resections (short gut or malabsorption syndromes with vitamin A, D, E, K deficiencies), kidney oxalate stones, gallstones or psychiatric disorders. The drug may reduce absorption of other medications making them sub-therapeutic (eg. epileptic, heart medications or warfarin).

Adverse reactions are mainly gastro-intestinal (fatty stools, flatulence, abdominal cramps) and hence the medication should be taken with low fat and low calorie meals.


Sibutramine (Reductil)

In Austtralia this drug has been withdrawn from the market because of the potential adverse cardio-vascular events (heart attacks and strokes).

This is an appetite suppression that blocks the re-uptake of neurotransmitters  (dopamine, nor-adrenaline, serotonin) within the brain but has adverse interactions with other drugs (eg. SSRI, MAOI) and potential serious side effects.





The keys elements to successful weight loss


Referral to consider bariatric surgery

We start the discussion on successful and sustained long term weight loss by emphazing the important role for surgery. Please read the section on “Understanding obesity and health issues” specifically about the benefits of surgery in reversing the chronic inflammatory and metabolic consequences of morbid obesity. From here on this section deals with just excess weight loss for simplicity.

The diet and exercise advice described above are potentially very successful and well circulated by the general practitioner, dietician, gym instructor, personal trainers and telemarketers but many do not appreciate that long term weight loss are not sustainable in the morbidly obese population.

A constantly fluctuating weight (especially in those with associated glucose intolerance or Type 2 diabetes) is most undesirable and potentially leads to erratic glycemic control, rapid or even more weight regain after brief initial success.

A referral to bariatric surgeon is often indicated for:

  • The severely obese patients (BMI > 35) with medical co-morbidities or the morbidly obese (BMI 40) with or without associated medical problems
  • Patients who have failed conservative measures or relapse (weight re-gain) after previous successful weight loss attempts
  • Patients identified as high risk to develop complications associated with metabolic syndrome



Requirements for successful weight loss

Having understand the reasons for obesity in our Western society, the management is simply to do the reverse.

  • Reduced calorie intake (achieve negative energy balance)
  • Increased physical activity (increase metabolic rate)
  • Long lasting behavioural modification (improved eating habits)


After initial success longer term behavioural modifications includes adherence to dietary guidelines, again emphasizing that the 3 keys elements are making good food choices, in correct portions and maintaining the good eating habits.

Although in the short term weight loss may be achieved by simple dieting and exercise (this is often recommended for people in the overweight category),  with medications (but beware of the potential side effects) but the majority who seeks specialist opinion are those who require bariatric surgery (after failure of the above measures and especially for those in higher BMI group with associated medical co-morbidities already alluded to above).

Laparoscopic sleeve gastrectomy and gastric bypass are considered bariatric and metabolic operations because of its restrictive effects (by physically limiting the amount of food that may be consumed) and its hormonal effects (due to favourable alteration in gut hormones resulting in satiety “neuro-endocrine brake”, improvements in blood sugar control via the entero-insular axis also known as the “incretin” effect amongst many other benefits of surgery).


Simply stated the aim of bariatric or weight loss surgery (not taking into account the metabolic surgery component) is to stop over eating (limiting amount of food consumed during each meal time), reducing hunger and maintain post prandial satiety longer to avoid grazing or snacking (limiting the total amount of food consumed during the whole day).

The reduction in caloric consumption creates negative energy balance which in turn results in gradual weight loss over the 6-12 months period after surgery. The post op patients often commented that their palate for highly saturated fat is reduced in prefernce for more healthy meals such as lean meat, fresh fruits and salds. The added benefit is positive behavioural modification and improved long term eating habits, helping to correct some eating disorders (as described above).





Long term sustained weight loss

Three periods of weight changes after surgery have been described described, listed below:

  • Active weight loss phase (usually in the first 3 to 6 to 12 months)
  • Weight stability phase (usually in the first 12 to 24 months)
  • Weight regain phase (usually after 3 to 5 years)



Weight loss after dieting alone without behavioural change will often result in weight regain or even greater weight gain in the medium to long term. The reason is multifactorial which may include:

  • Loss of lean body mass and resultant reduction in energy expenditure which tends to limit progressive or sustained weight loss before hunger centres override the desire to fast.
  • In the longer term some may develop unhealthy eating habits, progressively increase food portion size and the resultant physical adaptation that makes further weight loss attempts more difficult with the passage of time.


Bariatric surgery is more effective (sustained weight loss) than non operative measures not just because of its restrictive effect but also the lasting hormonal changes (eg. ghrelin, GLP-1, PYY) to aid behavioural change. The proof is that post op patients often are found to:

  • Have positive change (reduction) in meal pattern and size
  • Have altered palate  or modified taste (avoiding food with high fat contents and sweets)




Food intake and exercise after surgery

A dietician is important:

  • To provide ongoing education and support
  • To assist the individual’s to make the right food choices in the right portions to be consumed
  • To promote compliance to dietary guidelines and to prevent weight re-gain in the long term



Regular exercise is absolutely vital after surgery for the following reasons:

  • To reduce body fat (especially fat depots in the trunk) and preserve lean body muscle mass
  • To help maintain basal metabolic rate and improve physical endurance
  • Exercise helps to improve body image and self confidence, patients allocate more leisure/social time for activities that improves quality of life




Increased physical activity level (quantity and quality) post op is part of the overall behaviour change and has been found to be beneficial:

  • to assist weight loss initially
  • improve adherence to dietary advice and reduce sedentary lifestyle or behaviour
  • helps with body contour (to reduce body or truncal fat and help to preserve lean body muscle mass)
  • important for maintained weight loss in the long term and to prevent weight re-gain


The preferred exercise is aerobic type activity, to increase the activity of type 1a muscle fibers which favours greater energy expenditure. Gentle low impact exercise such as walking is recommended because it is less demanding, easily performed and done at no cost. Swimming, running and other sporting activities are moderately intensive and usually recommended once moderate or significant weight loss has been achieved.

In general aggressive resistance training (body building) which is intended to increase muscle mass should be avoided by most patients.