A DOCTOR'S GUIDE TO SUSTAINABLE WEIGHT LOSS

Carrying excess weight is a big issue in the UK and elsewhere in the world. About two thirds of adults in the UK are classified as overweight or obese and this brings with it a high burden of other illnesses which are caused or worsened by being overweight.

Our modern lifestyles, with low levels of activity and easy access to calorie dense, highly processed foods, are the driving force behind this rise in weight problems.

Many people struggle to lose weight despite the best of intentions because these same lifestyles are often busy and highly pressured which makes it difficult to undertake exercise and to spend time preparing the food that most of us know we should be eating.

Interest in sustainable weight loss has probably never been higher, both because it is such a widespread problem now, but also because new medications mean there are more options than ever before to help manage weight problems. 

Body Mass Index (BMI) is still the most common way to assess weight. Although there is a lot of debate as to whether this is the best measure of weight, it is still the metric that is used to set most medical guidelines. BMI is a calculation based on your weight in kilograms and your height in metres.

The NHS has a free BMI calculator that you can access here:

https://www.nhs.uk/health-assessment-tools/calculate-your-body-mass-index/

A healthy BMI is considered to be between 18.5 and 24.9. A lower BMI suggests that you are underweight. A BMI of 25 – 29.9 is considered to be overweight, and a BMI over 30 is considered to be obese. 

There are numerous health risks associated with being overweight. People sometimes talk about being ‘fat but fit’, but this concept is not really helpful when we consider all the problems that being overweight can cause.

Metabolic Problems

There are a range of metabolic problems that are caused by being overweight. Chief amongst these is Type 2 Diabetes, but being overweight can also cause

• High blood pressure
• Raised cholesterol
• Fatty liver disease

All of these issues will contribute to the development of cardiovascular disease including:

• Heart attacks 
• Strokes
• Peripheral vascular disease 
• Kidney disease

Body Mechanical issues 

Extra weight also causes mechanical issues and so being overweight is associated with back pain, osteoarthritis, lymphoedema, and a condition called Obstructive Sleep Apnoea in which the excess weight around the neck causes the airway to close repeatedly during the night leading to poor quality, unrefreshing sleep.

Cancer

It is perhaps also surprising that being overweight contributes to the risk of a number of cancers. Obesity can increase the risk of:

• Breast cancer
• Liver cancer 
• Kidney cancer
• Colorectal cancer
• Cancer of the womb
• Oesophageal cancer 
• Pancreatic cancer

Anxiety and Depression

Obesity is also linked to higher rates of anxiety and depression. The relationship between mental health problems and excess weight works in both directions. People often gain weight when they are low or anxious due to comfort eating and reduced activity, but people may also develop anxiety and depression because they are overweight.

For all of these reasons, sustainable weight loss should be a priority both at an individual level and at a population level. 

The two most important factors in sustainable weight loss are making changes to diet and to activity levels.

Diet

With regards to diet, calorie intake is a good rule of thumb to help guide daily food intake. In the UK, men are advised to eat about 2,500kCal per day, and women are advised to have around 2,000kCal per day. People who are trying to lose weight are recommended to reduce this by about 600kCal per day.

As there is a rapidly growing body of research into diet and nutrition, we are increasingly recognising that it is not just the quantity that people eat that is important, but what they eat is also very important. ‘Ultra Processed Foods’ are an enormous part of the problem. These foods are everywhere and typically include foods like snacks, ready meals, and soft drinks. They are usually high in sugar, salt and unhealthy fats, and low in nutrients like vitamins, minerals and fibre. Even if you stick to the recommended daily calorie intake but your diet is high in this type of food, you are still likely to develop health problems.

Activity Levels

The food we eat represents the energy that we put into our bodies. The other side of the equation is the energy that we expend through being active. Inactivity is a huge problem even if taken separately from being overweight. In the UK, the average working-age adult spends about 9.5 hours every day sitting down. About a quarter of adults undertake less than 30 minutes of activity each week. Being inactive is an independent risk factor for ischaemic heart disease, diabetes, breast cancer and colon cancer.

Becoming active does not mean that you have to join a gym or start running marathons. Activity is best achieved when it is built into your daily routine with simple things such as walking instead of driving short distances, or using the stairs instead of the lift. Public health guidance in the UK advises us to take about 150 minutes of moderate-intensity activity, such as brisk walking, each week. This is just over twenty minutes a day.

The biggest health benefits from increased activity come at the lower range of the activity scale. What this means is that, if you go from having no exercise to doing just a little bit each day, the health payoffs are enormous. If you are already very active and increase your activity levels further, you will still benefit but the change will be less dramatic.

When making changes to diet and activity levels, it is important to make these in gradual to help with sustainable weight loss. A sudden complete change in diet, or a new commitment to work out for an hour every day, are unlikely to be sustainable in the long run. You may achieve rapid weight loss initially but, if you start falling back into old habits, the weight tends to come back on leading to the ‘yoyo dieting’ with which many people are familiar. The general recommendation is to make changes that enable you to lose weight at about the rate of 2lbs or 1kg each week.

The landscape of sustainable weight loss has changed dramatically in the last few years. This is in large part due to the arrival of more effective weight loss medications.

For some time we have had the medication Orlistat. This is a tablet medication that stops the absorption of fat in the gut. It can be very effective, but its use is sometimes limited by gastrointestinal side effects.

More recently, weight loss injections have emerged. These have come from medications used to treat diabetes and they work by mimicking hormones in the body that have a role in appetite regulation. They are all weekly injections and their effect on weight can be dramatic. Studies for some, for example, show that people can lose up to of 25% of their body weight when the medication is used for around 2 years.

Generally these medications are licensed for use in people with a BMI over 30 or a BMI over 27 with a weight related health condition.

These medications are not for everyone. For some people, such as those with a history of certain cancers, the medications are not safe to use. Like any medication, some people also experience side effects with their use.

It is also important to remember that sustainable weight loss medications are just a tool. They are most effective when they are used alongside diet and lifestyle changes. Making these important changes will also ensure sustainable weight loss even after stopping the medication.