Obesity: Tricks to lose weight without starving yourself according to Professor Robert Thomas

Many people believe that obesity only develops as a result of consuming more calories than the body needs for metabolism and level of physical activity. As anyone struggling with weigh loss will testify, this "energy in and energy out" explanation is an over simplification. Complex genetic, medical, hormonal, gut health and psychological factors all influences body's need to eat and store excess energy.

Whatever the causes, across the world obesity rates have tripled over the last 30 years. In the UK, more than a quarter of the population are defined as obese (having a body mass index (BMI) greater than 30kg/m2) and nearly 60% as overweight (having a BMI of 25–30).

More worryingly, a report from the World Health Organization estimated that by 2030, the obesity rates in the UK would be over 50%. The UK’s National Institute for Health and Care Excellence estimates that obesity currently costs the UK over £5 billion in lost work production and medical management each year. It projects that this could rise to £50 billion per year unless this epidemic is prevented by effective government and societal interventions.

Being obese more than doubles the lifetime risk of hormone-related cancers such as breast and uterus, and also raises the risk of bowel, kidney and oesophageal cancers. Obese men are 33% more likely to die of cancer compared to those of normal weight, and obese women have a staggering 55% increased risk.

They are also more at risk from diabetes, blood clots, heart disease, respiratory problems and stroke. There are several underlying reasons for this. Obesity increases oestrogen and lowers progesterone levels.

It leads to insulin resistance/insulin-like growth factor receptor (IGF) and eventually diabetes. Carrying extra fat requires higher energy production leading to greater oxidative stress causing damage to the DNA. Obese men and women tend to have worse gut health, lower vitamin D levels and higher levels of chronic inflammation.

The causes of obesity are multifactorial. A person is more likely to develop obesity if one or both of their parents are obese. One genetic cause of obesity is leptin deficiency. Leptin is a hormone produced in fat cells, which controls weight by signalling the brain to eat less when body fat stores are too high.

Some medical conditions lead to obesity such as Cushing's syndrome (over production of steroids) and hypothyroidism (underactive thyroid) both which could be corrected with medical treatments. Low mood can lead to obesity because it demotivates people to exercise and eat healthy.

Many people eat excessively in response to emotions such as boredom, sadness or anger. Overweight people have 30% more psychological disturbances than normal-weight people but this is both a cause and effect, neatly summed up by a quote in the original the Austin Powers movie: "I eat because I'm unhappy and I'm unhappy because I eat".

Tips to lose weight

Avoid sugary foods and drinks

Sugary foods makes us pack on the pounds because they are high in energy source and are generally not satiating (make us feel full). We, therefore, we carry on consuming them even when our body has had enough calories. They also have a high glycaemic index (GI), causing blood glucose levels to increase rapidly. This stimulates insulin release by the pancreas, which promotes the storage of glycogen in the liver and eventually fat in the tissues tissue.

The initial high sugar levels tricks the body into thinking it has eaten a very large meal, so it overproduces insulin, which then causes sugar levels to drop, quite dramatically, which in turn stimulates hunger and fatigue. The natural reaction to this is to reach for another high-calorie snack or drink, which gives instant relief but this starts the process all over again- a vicious cycle.

Increase exercise and avoid sedentary behaviour

In western societies, the vast majority of people are not physically active enough, so many of the calories they consume end up being stored in the body as fat. It is particularly important to avoid long periods of sedentary behaviour both at work and at home and to move around as much as possible.

A good target is two and a half hours of moderate-intensity aerobic activity, such as cycling or fast walking, every week. The trouble is, if you are trying to lose weight, in addition to exercising you have to limit your calorie intake to no more than 2500 a day (for men) or 2000 (for women) to even start burning up energy stores. What’s more, this has to be sustained for many months to have any long-term benefit. Even the best exercise programmes achieve only 6% weight loss in 6 months.

Ideally, try to exercise first thing in the morning, before breakfast, even if only for 20 minutes. This means the stomach is empty, so the body has to use energy from stores in the liver and fat tissues. It also extends the period of overnight fasting which has been linked to a lower cancer and diabetes risk.

Eat more whole foods and fibre and less processed high-calorie foods

Processing foods, often high in fat and sugar, have the bulk and fibre removed reducing the need for chewing and allows them to be absorbed more quickly. Whole foods such as wild rice and whole meal bread which have to be chewed more have more bulk and fibre, making them slower to eat and more satiating, without increasing the calorie content.

Enhance your gut flora

Obesity is linked to an unfavourable profile of bacteria in the gut, known as dysbiosis. It has not been established, however, whether abnormal gut flora causes obesity or vice versa.

One theory is that the abnormal bacteria contribute to a state of stressful chronic inflammation, leading to low mood and fatigue, which demotivates individuals from pursuing exercise and eating less. Another theory is that, in response to increased inflammatory stress the nerves in the gut will tell your body to store more energy, preparing for a famine which of course never comes.

A study from Cornell University showed that the weight of mice could be changed by over 15%, just by altering their intestinal bacteria. Transplanting bacteria from the gut of obese humans into mice was found to trigger obesity in them.

Further research is required but until then, measures to improve gut health such as increasing dietary intake of fermented foods such as live unsweetened yoghurt, miso, kimchi, kefir or sauerkraut, and possibly taking a good probiotic supplement, would be a very sensible option.

Avoid snacking between meals

Hunger has become an unacceptable sensation in western societies, but it should be embraced, because this is when weight starts falling off. The fall in blood sugar that occurs when we’re hungry triggers the breakdown of glycogen in the liver and the conversion of triglyceride fats into fatty acids and glycerol to be used for energy.

Instead of grazing throughout the day, it is best to have a meal and allow it to digest completely before the next one. This also allows the digestive mechanisms to rest before the next meal, giving the gastric cells some downtime to repair rather than working flat out. If you do feel distressing hunger pangs, try drinking water, going for a brief walk or occupying yourself with an activity to help take your mind off food.

Add spices, herbs and blueberries to your diet

It is widely recognised that receptors in the stomach interact with capsaicin, a phytochemical responsible for the ‘heat’ in chillies, which helps with weight loss by signalling a feeling of fullness. Other phytochemical rich foods such as green tea, rich in catechin polyphenols has been shown to have many anti-obesity attributes, including controlling appetite, slowing the formation of white fat cells, encouraging the formation of the more healthy brown fat cells, and inhibiting fat absorption from the gut.

Blueberries and pomegranates are rich in phenolic acids and anthocyanidins, which have been shown to switch on fat metabolism and encourage weight loss even when the same number of calories are being eaten. Turmeric, the source of curcumin, can naturally down-regulate the production of an enzyme called acetyl CoA, which has the effect of reducing cholesterol and fat formation.

Extending the overnight fast

In one interesting laboratory experiment, a group of mice were given as much food as they wanted all the time, while another group had their food withdrawn for a few days every fortnight. The group that endured a modest degree of regular fasting maintained a normal weight and lived almost twice as long as the other mice.

In humans, the best evidence of effective fasting comes from a study that evaluated a large cohort of overweight women who had completed initial cancer treatments. The researchers discovered that those who adopted early dinners and late breakfasts, leaving 13 hours between the meals (without intermediate snacking), lost significantly more weight, had lower levels of glycated Hb (a marker of glucose control) and lower inflammatory markers. What’s more, after five years, they had a 36% lower risk of breast cancer recurrence.

In conclusion, maintaining a healthy weight will reap enormous benefits for immediate well-being and future health. It is certainly harder for people with a genetic susceptibility but it is still possible. It is important to be aware of the other factors which contribute to weight gain such as improving gut health, eating phytochemical rich foods, extending the overnight fast and exercising on an empty stomach.