Dear Dr Laura,
I’ve been struggling to lose weight – I’ve been looking into the options and I think fasting or supplements will give the quickest results. Are they safe?
There’s no easy way to say it – the only way to lose weight is to burn more energy than you consume. The main measure used to determine healthy weight is the body mass index, or BMI – your height to weight ratio. Normal BMI is 18.5-24.9, below 18.5 is underweight, over 25 overweight, over 30 (which applies to around 1 in 4 UK adults now) is obese. BMI isn’t entirely accurate, you can be very muscular with a high BMI but no excess fat; waist measurements can help decide. Obesity is linked to diabetes, heart disease, stroke and some types of cancer.
Ultimately all diets aim to reduce your calorie intake, by reducing/eliminating certain foods and/or limiting the time you spend eating through periods of fasting.
There are 3 main sources of food energy: carbohydrates/carbs, protein and fat. All have important functions; an optimal diet includes all 3 but the best balance is debated. NHS Choices promotes the ‘Eatwell guide’; in a nutshell it recommends getting most of your calories from fruit and veg and carbs (aiming for wholegrain and starchy carbs like brown rice, wholegrain pasta/bread/cereals and potatoes, rather than white rice/bread and sugar. Watch out for hidden sugars in foods (check those labels!). Some diets restrict or eliminate food groups, which can make it hard to get all your nutrients; consider a multivitamin/mineral supplement with restrictive diets.
There are LOADS of diets – searching Amazon for ‘diet books’ gets over 100,000 results. High protein diets where you reduce/avoid carbs and get more energy from protein are popular (e.g. Atkins and Dukan). There is evidence they work – the body uses more energy to break down high protein food and you feel fuller sooner – BUT there may be downsides: possible increase in heart disease, higher risk of kidney stones and concerns about kidney damage. These are less likely an issue if you follow this type of diet for a short time only.
Pros and cons of fasting are debated and a lot of trials are very small or in animals not humans. A better than average study last year compared alternate day fasting with ‘normal’ calorie-controlled diet in obese adults: there was no difference between the two. Another study in athletes showed what I’d consider ‘minor fasting’, consuming all your calories inside an 8-hour window of time, produced some minor metabolic benefits. Not eating all day can leave you feeling a bit lousy, skipping meals may mean you just eat more at others and prolonged fasting or severe calorie restriction can cause your metabolic rate to drop meaning you will gain weight more easily when you return to normal eating patterns –exercise will raise your metabolic rate. Again, this is likely less of an issue if you just fast for short periods of time.
Exercise has numerous benefits beyond weight. As well as lowering the risk of the conditions listed above, exercise helps improve mood, sleep and energy, is beneficial for bone strength and helps reduce dementia. NHS Choices (again!) is a good source for exercise advice but my main tip is to make exercise as normal a part of your life as possible. Walking whenever you can (some Tube stations are pretty close to each other), walking up escalators, using stairs instead of lifts and making exercise part of your social life (group classes, badminton clubs, long weekend walks followed by healthy pub lunches) will all help. Short bursts of vigorous activity are particularly important; this doesn’t need to be in a gym as there are numerous guides to high-intensity interval training (HIIT) and even a few minutes will do you good.
Finally, weight loss supplements… A survey last year showed that 1 in 3 dieters has tried weight loss supplements bought online. However, the Medicines and Healthcare products Regulatory Agency (MHRA) – the organisation responsible for medicines safety and regulation – warned that a lot of these websites are not regulated and the supplements may contain fake or banned ingredients. In 2016 the MHRA launched a campaign warning people about weight loss supplements; the year before they had seized almost 250,000 unlicensed slimming pills and closed down over 2,000 unauthorised websites.
Many online slimming pills contain sibutramine, an appetitive suppressant banned in Europe and the US since 2010, due to a risk of heart attack and stroke, but still available in some countries. Some diet pills contain DNP which speeds metabolism to the degree that it can cause fever, collapse and death. Despite DNP being ruled ‘highly dangerous’ in 1938, it was listed as a cause of 15 deaths between 2007-2016, a likely underestimate since for unexpected deaths, online medication use may never come to light. The only licensed medication for weight loss in England is Orlistat which binds to fat in food to reduce the amount you absorb – instead of entering the blood stream it comes out your bottom instead which can result in oily poo (difficult to flush!), excess wind and even poo leakage. Orlistat can be prescribed or bought over the counter from a pharmacist but should be considered a plan B if diet/exercise have not worked; as well as side effects, it can interact with some medications and reduce absorption of some vitamins.
So, my advice is avoid online diet supplements, kick start your weight loss with a high protein/low carb diet for a few weeks then switch to a balanced diet as recommended on NHS Choices. Keep a food/activity diary and, even if you have no time for dedicated exercise, get as much exercise through your daily activities as you can. Sustained changes to your lifestyle will get better long-term results than quick fixes.