Weight Loss - The Basics
Losing weight can be challenging. A survey in the US found that only one in six overweight adults who succeeded in losing 10% of their weight kept it off for at least a year. By this point, none of the volunteers were sticking closely to a diet and many had gained back most of their lost weight. So what conspires to stop us losing weight and what can we do to make meaningful long term improvements?
The increasing weight profile in society has mirrored the change in our diets. There has been a steady move to ultra-processed foods (soft drinks, chocolate, candy, ice cream, sweetened breakfast cereals, packaged soups, chicken nuggets, hotdogs, fries and more). Ultra-processed foods are on the rise globally, and in the US and UK they account for over half of all the food consumed. Food experts are universally agreed that these types of food are behind the obesity pandemic. We can choose to get these ultra-processed foods out of our homes.
When our diets are high in cakes, ready meals, potato chips and sugary beverages, this disrupts our metabolism releasing an unnaturally high amount insulin, the hormone that keeps blood sugar levels under control. Glucose sugar is highly reactive, so our bodies normally keep the amount in the blood within a narrow range. The excess insulin causes our fat cells to take in and store too many calories, leaving fewer available for the rest of the body. A few hours after eating, the number of calories in the bloodstream plummets, so we get hungrier sooner compared with eating natural unprocessed foods which release less insulin.
Before going too far, let's consider what being overweight is. Standard advice is that anyone with a BMI (Body Mass Index - a height to weight ratio) over 25 is overweight, and a BMI over 30 is obese. This is cemented in medical advice but no-one knows where it came from. A more evidence-based approach is putting overweight at 30 or higher. This is relevant as it accounts for about half of those who would currently be medically advised to lose weight. Multiple tests have shown that people with a BMI between 25 and 30 live longer than those with an officially healthy 18.5 to 25 BMI. Even the raised risk of getting covid-19 does not kick in until your BMI is above 35.
Understanding the impact of food on our bodies is complicated. The combination of foods you eat, how much you eat and when you eat can have a huge impact. If you don't control for this food-matrix effect then one person might absorb a lot of a substance and another very little. With so many variables it is hard for even large clinical trials to draw clear conclusions. On top of this individuals respond differently to diets due to their genes or gut microbiome. All diets are about reducing calories but often this is disguised. In one US study, 160 adults with obesity were randomly assigned to four different diets and no differences were found in the ease with which people adhered to their assigned diet, nor in the weight loss or health benefits obtained. The trick is to find a diet you like and can stick at. Don't expect it to work for everyone as we are all different.
We often hear that exercise is good for losing weight. The trouble is our bodies are designed to keep the number of calories we burn and consume every day in a narrow range. We adapt to exercise, burning a similar number of calories whatever our activity level. Weight loss starts well with a new exercise regime but fades over time. In a 16-month long trial, men and women burned 2,000 calories a week on a closely monitored exercise program. After nine months, the men had lost 5 kgs on average and then their weight plateaued. The women lost nothing over the 16 months. The reason the weight loss bore no resemblance to all the calories burned is because our metabolisms adjust (quieter immune system, lower resting heart rate and more). From an aesthetic point of view, having more muscle, even with a high fat percentage, can look better. Although exercise may not be a major factor in weight loss it still provides many health benefits.
The impact of sleep on weight is significant. Sleep loss affects our decision making leading to poor food choices and less exercise. It also depletes the hormone leptin which inhibits hunger and increases ghrelin which makes us hungry. Poor sleep interferes with other hormones too that cause people to put on fat and lose muscle mass.
Another cause of weight gain is stress. The hormone cortisol is released in response to a physical or mental threatening situation. Constant stress causes too much cortisol to be released which in turn causes increased appetite, poor lifestyle choices and sometimes insomnia. Exercise is highly beneficial in stress reduction.
A key reason for weight gain in middle-age is hormonal change. During the female menopause, oestrogen decreases causing visceral fat to increase. Hot flushes can lead to insomnia and there is risk of depression and anxiety which also interfere with sleep. Low testosterone occurs in a quarter of men over 45. It can be caused by injury, obesity, diabetes, cancer, medication or just plain aging. Low testosterone leads to less muscle mass and more abdomen body fat.
Should periodic fasting feature in a weight loss program? Biologically this makes sense. A fasted state starts 10-12 hours after your last meal. Your body runs out of glucose and your liver breaks down stored fat into ketones for energy. This metabolic switching raises your metabolism helping lose weight. This process gives the body a chance to use up fat stores rather than responding to less calorie intake by reducing muscle mass, which the body considers a high energy luxury. Another way to put your body in the fat burn ketosis state is to go on an ultra-low carb diet (20 - 50 grams of carbs per day). Ketosis should cut in after 3 to 4 days. If you are interested in checking whether your body is getting its energy from fat or carbs, there is a device called "lumen" which can tell you. A good thing about ketosis, apart from fat burn, is that it supresses mTOR which normally promotes cell growth and reproduction and allows for cell clean up and repair processes to occur. If glucose constantly floods to bloodstream this will never happen.
Our bodies respond to lower calorie intake by reducing our metabolism. This starts a couple of weeks after we go on a diet and higher adaptation occurs 3 to 6 months after dietary restriction. In short, after a good start it becomes ever harder to lose weight. If you want to lose a lot of weight, then you have to accept that change will be slow and you are in for a long haul. Permanent lifestyle changes are required otherwise the weight will bounce back.
Our perception of how filling food is has been shown in several experiments to influence how hungry we are. When participants were given a “healthy” chocolate flavored protein bar they reported feeling hungrier than people given the same bar described as “tasty”. They even felt hungrier than people who had eaten nothing at all. In another test involving shakes and healthy verses indulgent descriptions, people's ghrelin levels were measured. Ghrelin is known as the hunger hormone and affects how hungry we feel. When people drunk the “indulgent” shake their ghrelin levels dropped as expected. We people drank the same but supposedly “healthy” shake their ghrelin levels hardly changed. There were clear hormonal changes based only on people's perceptions.
Our microbial cells (bacteria, viruses and fungi) live all over us and inside us. They are collectively called our microbiome and are most common in our guts. Having a diverse microbiome is good for digestive, physical and mental health. That means everything from weight management to heart health, depression and more. A poor diet and overuse of antibiotics can harm our microbiome. A healthy microbiome is cultivated by a broad plant-based diet. These prebiotics are mainly fiber or complex carbs that human cells cannot digest. To repair a damaged microbiome, take probiotics which are live bacteria and yeasts which are usually added to yoghurts or taken as food supplements.
The science around artificial food sweeteners is showing many of these ingredients are not benign. They can affect our metabolisms through hormone release or through our microbiomes that make us gain weight. Research is ongoing.
Many of us take food supplements. With a broad-based healthy diet, you would expect to get all the nutrients you need. There can be problems from getting too many vitamins or minerals above the recommended daily dose. People taking several different supplements may not realise how much they are overloading. Foods contain more than the nutrients you would find in a typical supplement. Plants contain phytochemicals that minimise cell damage by free radicals. These would be missing from a diet of processed foods supplemented by multivitamin pills. The food environment matters. For fat-soluble vitamins A, D, E, and K they need to be dissolved in fat to be transported into the blood so take vitamin tablets with food.
There are weight loss drugs. Semaglutide was approved by the FDA in June 2021, the first weight loss drug approval in seven years. In a 68-week trial, giving weekly injections to 2,000 obese people, those given the drug lost 15% of body weight on average compared to 2.4% in the placebo group. There were significant side effects though in a large proportion of participants such as nausea, diarrhoea and vomiting. To maintain the weight loss, you would need to take the drug for the rest of your life. Semaglutide targets both the brain and the body in its effects unlike older drugs that target just one aspect. Those solutions typically gave weight loss of around 5%. The most effective way to lose weight seems to be to have weight-loss surgery, which shrinks the stomach or redirects the gut. This is quite severe and has risks beyond just surgery. 10% of people undergoing surgery developed another addiction, such as alcoholism, to replace overeating.
Actions to lose weight
The first action to fight excess weight is to get good sleep. Have at least 7 to 8 hours sleep otherwise you will be making bad choices while trying to diet and fighting against messed up hormones making you hungry. Get a regular sleep pattern and if you have insomnia address it with cognitive behavioral therapy rather than pills.
Pick a diet plan that you will enjoy, low-carb, low-fat or simply balanced natural produce, all of which will be lower in calories than your current level. Do choose fresh produce over processed foods which are packed with sugar, salt and saturated fats.
Even though exercise will have little direct impact on your weight it still helps in other ways. It has been shown to lower the production of stress hormones which can help with sleep and stress eating. Exercise will help maintain muscle mass which stabilises metabolic health and makes us look better.
Do a daily fast most days, eating no calories for at least a 12 hour window. A keto diet for at least 5 days will also induce the fat burn response.
Avoid liquid calories. We expect liquids to be less satisfying than solids even if they have the same calories. High sugar sports drinks have more calories than you expect especially combined with the health focused labelling. Meal replacement shakes are the same.
Pay attention to taste and texture and presentation of your food. If you are on a diet and think you are sacrificing your enjoyment of food, rather than being a treat you look forward to, then you will just want to eat more.
Giving more thought to eating by eating more slowly and chewing more can trigger a greater hormonal reaction and leave you feeling fuller for longer. Realise that you can get all the pleasure from a smaller portion.
Remember you need to look after your microbiome for all round good health.