How does weight loss affect your body composition?
When you lose weight, you lose fat. However, you also lose muscle and other body tissue – known as lean body mass (LBM).
LBM is everything in your body apart from fat – e.g. muscles, bones, organs, blood, and skin. A reduction of LBM is bad news for your health.
As you lose LMB, you become fatigued, your muscle power and efficiency decreases, and in older people, this increase the risk of accidents and falls. As your LBM declines, your resting energy expenditure also falls, meaning you generally burn less calories during the day.
Many people who lose weight on a diet, find they feel tired, their weight loss plateaus, they become disheartened, give up the diet, regain all the weight they lost and more. However, very importantly, they also fail to regain their lost LBM.
This is why when you follow any weight-losing regime, you should aim to optimise the loss of fat and reduce your loss of LBM.
How can you lose more fat and less LBM?
Follow these 8 recommendations –
Choose a diet you can stick to – and follow it
No diet is ‘best.’ In a 2018 paper in the journal Nutrients, the authors compared the proportion of fat and LBM lost following adherence to a range of popular diet programs – the Very Low-Calorie Diet (VLCD), Low Carb Diet, Low Fat Diet, High Protein diet, and the High Fiber Diet.
Overall, the weight loss from each of these diets resulted in a percentage loss of around 75% fat, and 25% LBM (See Table 1).
This was apart from one exception – the High Protein diet. In this diet, participants consumed at least 2g protein/kg body weight/day. They lost an incredible 89% fat, and 11% LBM. The study subjects also undertook a resistance exercise program, three times a week.
Experts now believe that when calories are restricted, protein intake should be increased to maintain LBM.
The High Fiber diet has also much to commend it Fiber is the part of fruit and vegetables which your body cannot digest. This ‘roughage’ passes through the digestive tract and out the other end in your stools.
High fiber diets do have specific additional benefits. For example, fiber binds to dietary fat and helps decrease fat absorption. Adding fiber to your diet, also helps you feel full for longer, and feel less hungry.
Table 1: Percentage of fat and LBM loss for a range of diet programs
|% Fat Loss||% LBM loss|
|Very Low-Calorie Diet||75||25|
|Low Carb Diet||76||24|
|Low Fat Diet||76||24|
|High Protein Diet||89||11|
|High Fiber Diet||75||25|
Willoughby S et al, Nutrients 2018; 10(12) 1876
Increase your levels of physical exercise – and start resistance training
To achieve the best outcome from any weight-losing regime you must not only restrict your calorie intake – but also increase your amount of physical exercise.
In order to lose weight, The American College of Sports Medicine (ACSM) recommends –
- For modest weight loss, 150-250 minutes of moderate-intensity exercise per week
- For substantial weight loss, over 250 minutes of moderate-intensity exercise per week
Moderate-intensity exercise is any exercise which makes your heart beat faster and makes you slightly sweaty and out of breath, for example walking briskly.
Any exercise is good exercise – as far as weight loss is concerned. The numerous health benefits of exercise are well established. Regular physical exercise is highly effective in the prevention of cardiovascular disease, diabetes, high blood pressure, cancer, dementia, depression, and osteoporosis.
When you consider the effect of exercise on weight loss, bouts of exercise increase your resting metabolic rate. This in turn, increases your post-exercise oxygen consumption, and this persists even after exercise has stopped.
Avoid sitting at your desk for long periods. You should get up once an hour and walk for a few minutes, or run up and down the stairs a few times. Consider a ‘sit and stand’ desk. What about an under the desk treadmill or pedal exerciser? Walk in your coffee breaks and lunch breaks. Use a pedometer – whatever they say in the press, it does stop you being so sedentary.
However, if you want to specifically increase fat loss and reduce the loss of LBM – you should consider doing resistance training.
What is resistance training?
Resistance training means any type of exercise where your muscles are acting against a force. This does not necessarily mean you need to join a gym – it’s quite possible to do a simple exercise program at home, in which your body is resisting its own weight and force.
How does resistance training affect fat loss and LBM?
A 2018 review in the journal Nutrients compared the results of 6 randomised controlled trials, looking at the effects on weight loss and loss of LBM in groups who were calorie-restricted and on a range of different diets, coupled with resistance training.
The results showed that resistance training, when associated with any form of calorie restriction, prevented almost 100% of the usual calorie-restricted muscle loss.
Various reasons were proposed to explain this finding.
During calorie restriction without exercise, there is a breakdown of protein and reduced protein synthesis. Resistance training directly stimulates protein synthesis. Because exercising muscles need energy, this energy is derived from fat breakdown and used for protein building.
To top this further, if you add in extra protein to your diet, when undertaking a resistance training regime, this can also have additional benefits in the maintenance or increase of LBM. Having a protein shake while actually working out, may be beneficial.
There are also physiological benefits of resistance training. For example, it has been shown to improve glucose metabolism and result in lowered levels of cholesterol.
Take note that resistance training does not just improve muscles – it also improves bones. It will help increase your bone mineral density. Your bone health is also vitally important.
How to get started with resistance training
There is a lot of helpful advice about resistance training on the internet.
Why not take a look at Resistance Exercises for Beginners with Justin Reeson on YouTube.
Take note, you can do this at home. You do not necessarily need to join an expensive gym.
A few sessions with a personal trainer may be useful to get you started.
Drink plenty of water – drink at least 2 litres per day. More when exercising.
Dehydration slows fat breakdown and reduce new muscle synthesis. Drink 2 litres of water a day and more when you are exercising.
For example, in one 2012 study of those following a calorie-controlled diet, those who drank 500 ml water before every meal had a 2kg greater weight loss over 12 weeks, than those who did not.
In one study, 98% of a US football team were found to be dehydrated when they attended for their morning training!
A 2% reduction in hydration can reduce your performance by 25%.
Current recommendations for water consumption when working-out
- 500-600 ml water half an hour before exercise
- 300 ml 15 minutes before
- 240 ml every 15 minutes while exercising
Add extra fiber to your diet – eat more high-fiber foods or take a dietary fiber supplement
Research confirming that additional fibre specifically helps conserve LBM is limited.
However, in a 2012 study in which rats were fed a high-fiber complex for 6 weeks, the investigators noted the high-fiber diet, did induce some physiological changes to preserve LBM. For example, they noted a direct increase in mitochondrial synthesis. Mitochondria are the sites within each cell, where energy from food is turned into power.
Another 2012 placebo-controlled trial studied the effect of a natural fiber complex – Litramine IQP G-002AS (Opuntia ficus-Indica – cactus fiber) enriched with additional soluble fiber from Acacia (gum from the Acacia tree). The group who took this fiber complex lost 5% more weight than the placebo group and lost significantly more body fat.
Consider other supplements such as chromium picolinate
Chromium is a trace mineral, essential for normal body function. Human beings are quite frequently deficient in chromium because dietary intake of chromium is often low, and absorption is poor from the gut. Chromium deficiency seems to impair glucose metabolism.
Foods rich in chromium include broccoli, grape juice, whole wheat muffins, potatoes, garlic, and basil.
The effect of chromium supplementation on weight loss is controversial, however, there is some evidence to show this may be beneficial. It does not appear to be harmful.
Chromium supplements have been shown to aid weight loss and reduce the loss of LBM. For example, in one small, double-blinded trial (1997) a group of obese subjects on a very low-calorie diet were followed for 26 weeks. All subjects lost weight, but the loss of LBM was a statistically significantly reduced in the group taking a chromium picolinate supplement.
Another double-blind study (1996) of swimmers, followed 2 groups of competitive swimmers, who were not dieting, for 24 weeks. One group took chromium supplements, the other group took a placebo. The chromium group decreased their fat mass by 4.5%. but also increased their LBM by 3.5%, compared to the placebo group.
Drinking green tea
Catechins are plant compounds found in green tea, thought to have weight-losing properties, especially when mixed with caffeine.
Various studies support the fact drinking green tea aids weight loss. In fact, drinking green tea may also promote loss of abdominal fat, and reduce the loss of LBM.
A 2009 double-blind, randomised controlled study, in the Journal of Nutrition, reported on 2 groups of subjects; one group drank a beverage containing catechins and caffeine, and the other group drank the same beverage however it contained caffeine only and no catechins. Both groups were asked to maintain a steady calorie intake and to exercise 180 minutes per week.
Both groups lost weight, and there was no statistically significant increase in weight loss in the catechin group. However, of interest, significantly more abdominal fat was lost in the catechin group.
Get 8-9 hours sleep a night
This is something you really need to be aware of!
In a 2010 randomised, cross-over trial study in the journal Annals of Internal Medicine, the authors took a group of 10 non-smokers with an average BMI of 27. Half were allowed to sleep only 5.5 hours a night for 14 days, and the other group 8.5 hours, and then the two groups swapped over. All the participants followed a calorie-restricted diet.
Guess what? – The group who slept for 8.5 hours per night lost twice as much body fat as those who only slept of 5.5 hours. The group who were sleep-deprived lost 60% more LBM than the other group. The authors propose that sleep is essential for the maintenance of LBM.
Use of smartphone apps
Some people have found using smartphone apps useful for weight management. Recent research reminds us to beware. Many apps have not been developed with input from health or fitness experts and their techniques are not evidence-based. However, if you find it helps motivation and encourages you to stick to the program, this must be a good thing.
Last few tips
Stay focussed, stay motivated, keep calm. This will take time – it will not happen overnight. A slow gradual weight loss, with better muscle strength, and improved overall health, is the desired outcome.
Yes, you can do it! Off with the fat and on with the muscle!
Dr Deborah Lee
Having worked for many years in the NHS, mostly as Lead Clinician within an integrated Community Sexual Health Service, Dr Deborah Lee now works as a health and medical writer, with an emphasis on women’s health, including medical content for Dr Fox. She has published several books and remains passionate about all aspects of medicine and sexual health.