What is a skinny fat person & how to overcome it?
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You’ve probably heard someone been called skinny fat. It’s a term considered not-so-politically-correct by many. The acronym TOFI is also used, although less commonly, and it stands for Thin-Outside Fat-Inside.
What is skinny fat?
Despite being an oxymoron, the term skinny fat refers to someone who looks pretty normal or even skinny in their clothes, but who actually holds a large percentage of body fat. They’re also lacking in muscle mass. Because of their poor body composition they will encounter many of the same health problems as an obese person may.
Technically speaking, this is a medical condition known as sarcopenic obesity — a condition whereby an individual has low muscle mass, low muscle strength, accompanied by a relative excess of fat mass . Essentially, you are metabolically obese while having a normal weight.
A quick aside, this is why it’s better to talk about fat-loss than weight loss per se; a skinny fat person who improves their body composition – losing fat and/or gaining muscle mass – may remain weight stable or even increase their weight.
Having too little muscle mass and too much fat, regardless of your weight, is unhealthy. It goes to show that just because you’re skinny on the outside, doesn’t mean you’re healthy on the inside. A metabolically obese individual, or someone who is skinny fat, can have the same BMI as a person who is extremely muscular and/or lean. Typically the skinny fat person will also hold excess visceral fat.
Did you know?
There are many types of fat in the body, two of which are of particular interest here: subcutaneous and visceral fat.
Subcutaneous fat is the type of fat we can grab and see on someone. It often masks as belly fat or a gut. It’s located between the skin and abs (outer abdominal wall). Everyone has subcutaneous fat and lifestyle factors such as diet, activity, stress, sleep and genetics largely determine how much subcutaneous fat someone has. There is evidence suggesting that subcutaneous fat plays an important role in modulating peripheral insulin resistance through its action on visceral fat accumulation . It’s useful to think of fat as being both part of the immune system and metabolism. It’s our body’s main energy buffer and dispenser. It has important roles in mediating inflammation [3,4].
Visceral fat, on the other hand, is in the spaces between the abdominal organs and in an apron of tissue called the omentum . While fat is still fat, regardless of its location, studies have shown that visceral fat accumulation is significantly more metabolically harmful than subcutaneous fat . Indeed, visceral fat is linked to metabolic disease, insulin resistance, and increased risk of death regardless of BMI.
What’s the problem with visceral fat?
Visceral fat is very close to the inner organs, and its storage capacity is also limited. Hence, its inflammatory action directly impacts organs such as the liver and pancreas . The liver has an awful lot of functions, but storing fat is certainly not one of them. Fat in the liver interferes with the vital functions of the organ and leads to lipotoxicity .
The liver itself can become insulin resistant . In this state it releasing blood sugars in an uncontrolled manner and further stimulates insulin release, leading to a vicious cycle. This makes it very difficult to control blood sugar and is one of the reasons why a fatty liver is strongly associated with diabetes.
As mentioned before, visceral fat releases pro-inflammatory cytokines, leading to low levels of chronic inflammation throughout the body . Chronic inflammation is thought to further contribute to insulin resistance and is a risk factor for cardiovascular disease, cancer, diabetes and nearly anything bad you can name [11,12,13,14]!
All in all, to no longer be skinny fat you have to focus on improving your body composition, not weight loss. This can be extended to classical overweight obesity too. In fact, one study estimated that close to half of “clasically” obese people (43% of females and 42% of males) are skinny fat !
Why are some people skinny fat?
As mentioned above, while people who are skinny may look normal on the outside, they carry an unhealthy amount of fat, especially located around their organs which poses a serious health threat.
But there are specific reasons why some people may be skinny fat while others are not.
Calorie and protein restriction — too much of either isn’t good
One of the biggest mistakes people make when trying to lose excess body is making calorie restriction their number one approach.
Studies have shown that when you cut calories excessively the body adapts by using fewer calories, thus negating your intention to be in a significant caloric deficit [16,17]. This is more commonly known as metabolic adaptation. At the extreme end, it’s known as the body’s starvation response. This metabolic slow down is an adaptive response you evolved. It preserves energy for crucial processes like immune system activity, as well as for maintaining a healthy reserve of energy (fat stores) [18,19].
With this in mind, it’s maybe not so surprising that when excessively calorie restricting, a significant fraction of the calories you consume during this adaptation process are shunted towards fat stores rather than muscle tissue. Again, this ensures the body has enough reserves to keep you alive in case a situation where food is lacking. As this study showed, restricting calories 25% without resistance training and even when eating a relatively high amount of protein (1.7g/kg of body weight per day) doesn’t preserve lean mass well .
One study sums it up well, saying “A weight loss diet in this population [of skinny fat people] should therefore always focus on the preservation of muscle mass and could be combined with a high protein diet and/or micronutrient supplementation” . We at Nutrita have a different definition of ‘high protein’; we take > 1.6 g/kg of body from animal foods as a generous starting point. The quoted study however defines it as > 1.0 g/kg of body weight (and not necessarily from animal foods).
Overtraining, in the form of excess endurance training
Endurance training is great to keep the cardiovascular, respiratory and metabolic systems functioning well. Too much however, in the context of under-resting, can be detrimental to your health. When we put the body in a state of physical stress without adequate periods of recovery, our stress hormones become harmful rather than good signals for our body to go through its health and performance adaptations.
Excess endurance training or rather, a lack of rest, keeps stress hormones too high too often and may blunt appetite. This can create too much of a caloric deficit, further exacerbating the issue. Remember, although exercising feels like your burning a ton of calories, you actually aren’t. It’s understandable and easy to confuse perceived effort with calories burned.
Ultramarathoners aside, enduring training doesn’t cause you to burn that many calories (i.e. enough to put you in a severe deficit). The issue with endurance training for a skinny fat person is that it’s not a good approach to build muscle mass – something they’d do well to focus on. If you partake in long bouts of intense endurance efforts frequently, you may well be misplacing your efforts. The problem is not endurance efforts per se, rather it is the lack of focus on improving your body composition by increasing your muscle mass through resistance training.
Research suggests that it’s better to select high intensity and resistance type training when going for excess body fat loss and muscle gain simultaneously (i.e. improved body composition) [22,23]. The combination of a higher protein diet and resistance training is so important that muscle mass can be preserved in a slight caloric deficit .
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Are you skinny fat?
If you know you have some visceral fat but aren’t quite sure if you fit into the category of skinny fat, here are a few ways you can test. Surprisingly, there doesn’t seem to be agreed upon values to objectively diagnose you with sarcopenic obesity! Here are some tests listed in order of most to least reliable.
1) Hydrostatic Weighing and DEXA Scan
Clinical measures are one of the most accurate methods of determining body composition.
Hydrostatic weighing, also known as underwater weighing, is a method used to determine total body density. It is based on the Archimedes Principle you may have learned in high-school . Lean tissue (bone and muscle) is more dense than water, and fat tissue is less dense than water, so essentially muscle sinks and fat floats. Therefore, a person with higher body fat levels will weigh less underwater than someone with less fat and more muscle for a given volume.
Dual-energy x-ray absorptiometry, more commonly referred to as DEXA, is a highly accurate imaging technique for measuring body composition with a very minimal margin of error. It uses two kinds of x-ray beams. The lower intensity beam is only absorbed by soft tissue (muscle and fat) whereas the high intensity beam is absorbed by bones and soft tissue. The differences in absorption is used to determine bone mineral density (BMD) and body composition values.
2) Callipers (if used by an expert)
Skin callipers are one of the cheapest and easiest forms of determining body composition by measuring the thickness of skin including the underlying layer of subcutaneous tissue (fat). They are taken at four specific sites on the body: the tricep, bicep, subscapula, and suprailiac crest. The sum of all four locations is determined and compared to a table of body fat percentages for specific age ranges to determine overall body fat percentage.
3) BIA Scales
BIA scales are a non-invasive test that involves placing two electrodes on the person’s right hand and foot. They can also be conducted by standing on an electrical scale and holding the electrodes, after which a low level electrical current is sent through the body. The flow of the current is affected by the amount of water in the body. Tissues that contain large amounts of fluid and electrolytes, such as blood, have high conductivity, whereas fat and bone have low conductivity.
As BIA determines the resistance to current flow as it passes through the body, it provides estimates of water content in the body, which body fat percentages can then be calculated from. You’ll see these most commonly used in gyms, they’re quite commonly nowadays. They may be directionally accurate but we don’t recommend them as an accurate measure of body composition. This is because changes in hydration, amongst other variables, can interfere with the readings.
What makes you skinny fat?
Becoming metabolically obese doesn’t happen overnight. It’s an accumulation of poor lifestyle choices that result in the loss of muscle mass and gain of fat. But being skinny fat doesn’t just happen for a certain population or age group — it can happen to anyone.
The main problem with being skinny fat is that most people are not aware of it. Being obese with a high BMI is quite obvious, and it is widely known that obesity is associated with many risk factors. For this reason, it’s much harder to convince a slim person to make significant lifestyle changes.
How come some people become visibly obese but others stay slim on the outside whilst being fat on the inside?
Usually, fat is supposed to be stored as subcutaneous fat. Subcutaneous fat is energy storage or energy buffer. The problem is that the amount of fat that can be stored in these subcutaneous stores is limited and very little will accumulate if the fat tissue happens to be insulin resistant. Fat tissue expands with the help of insulin. Insulin is a storage hormone, and as long as insulin is high enough, energy is either taken up, stored as glycogen in muscles and liver, or as fat in fat tissues. The amount of energy that can be stored as glycogen is very limited, but fat tissue can expand via adipogenesis (the creation of new fat cells). However, fat tissues cannot grow indefinitely . When they come closer to reach their capacity, fat cells become less sensitive to insulin .
Some people store lots of subcutaneous and visceral fat. It’s also the case that when subcutaneous fat gets closer to its maximum storage capacity, visceral fat tends to suck up more fat to compensate.
In obese people, subcutaneous fat tissue has a big expansion capacity. In skinny fat people, only small amounts of fat can be stored as subcutaneous fat. This is because their adipocytes (fat cells) have a more limited capacity to expand – they’re resisting the action of insulin which is to take up more fat and stop its release into the bloodstream.
Because visceral fat is a risk factor for diabetes, obesity can literally be protective against diabetes by sparing visceral fat storage and the hyperinsulinemic cycle .
Why some people become skinny fat rather than obese is not well understood. There seems to be a personal fat threshold that is strongly determined by genetic factors, but this doesn’t explain why some people manage to be both diabetic and very obese . While people who stay slim, despite eating junk food and not exercising tend to call themselves lucky, quite the opposite is true. They feel safe because they don’t see the usual warnings of such a lifestyle, which leads them to put their health at risk.
It’s a well known fast that as we age, body composition begins to change. Studies have shown that around the age of 30, muscle mass and strength start to progressively decline, with it being more accelerated after the age of 60 .
2. Lack of exercise (especially resistance training)
A sedentary lifestyle is not only a risk for several detrimental health conditions, but it also increased the chance of becoming skinny fat . People with a higher body mass tend to be less active in general, which may contribute to loss of muscle mass and strength. Furthermore, low physical activity can lead to muscle atrophy. In this case, atrophied muscles result in decreased metabolic rate both at rest and during physical activity, which can result in a poorly functioning metabolism. The latter skews energy partitioning away from muscles and more towards fat tissue.
Studies have shown that increasing physical activity and dietary improvements along the lines of what Nutrita recommends can lead to increased muscular strength and mass, in addition to fat loss in obese populations .
3. Chronic inflammation
Evidence shows that adipose tissue secretes different hormones and proteins. For example, the release of pro-inflammatory cytokines (TNF-alpha, IL-6) and adipokines such as leptin and adiponectin from adipocytes up-regulate the inflammatory process within the body. A study conducted in 2005 found that pro-inflammatory cytokines were associated with increased fat mass and decreased muscle mass .
4. Pathological insulin resistance
As insulin acts as an anabolic agent within the body and helps build muscle, pathological insulin resistance may make it harder to keep your existing muscle mass . Resistance training has been shown to improve insulin sensitivity and blood sugar control .
5. Anabolic resistance
A recent study has shown that individuals with sarcopenic obesity have lower levels of growth hormone secretion, as well as lower testosterone levels . This is called anabolic resistance and correlates with decreases in muscle strength and mass.
6. Chronic stress
Chronic stress also plays a part in the progression of being skinny fat. When the body is put under stress, whether that’s physical, emotional, or mental, the sympathetic nervous system is activated and releases cortisol, adrenaline and other hormones. The immediate effect is:
- Increased breathing rate
- Increased blood pressure and heart rate
- Slowed digestion — blood is diverted to muscles rather than the digestive system
- Sex hormone production halts
- Glucose and fat are released into the bloodstream
Chronically elevated levels of the stress hormone cortisol can wreak havoc on the body. It promotes the breakdown of muscle while also the storage of fat, the perfect combination for becoming skinny fat. Specifically, chronic cortisol elevations are consistently associated with higher belly, VAT and SAT fat [37,38,39,40].
Testosterone is also suppressed during the stress response and is needed to gain muscle. Without it, there’s an increased risk of developing abdominal fat and a much harder time keeping or packing on muscle.
Not consuming enough high-quality protein severely impedes the process of muscle growth and repair. This contributes to lack of muscle development and thus decreased muscle mass. The most consistent study findings show: an increased susceptibility to central adiposity (beer belly), lower fat oxidation, lower energy expenditure, insulin resistance and a higher risk of diabetes, hypertension and dyslipidemia in adulthood .
How to get rid of ‘skinny fat’
Just like trying to get rid of abdominal fat, or fat in any other region, getting rid of ‘skinny fat’ takes about the same amount of work; it’s all about reducing the amount of visceral fat present in your body.
Here’s how to get rid of visceral fat.
1. Keep moving — exercise regularly
Don’t move to “burn calories” to achieve a caloric deficit. Burn calories in a way that sends the right signals to your metabolism and hormonal systems. While any form of exercise is recommended to maintain health, high intensity interval training (HIIT) has been shown to be the most effective for reversing skinny fat. Many studies have shown that higher intensity exercises, like those done in HIIT workouts, are more effective at burning fat than doing hours of endurance training, especially for decreasing visceral fat [42,43,44].
The afterburn effect, also known as the EPOC effect, is also put into play here, whereby the body continues to burn calories even after exercise has stopped. Research suggests that, compared to lower intensity activity, more intense activities done at a heart rate >70% max. burns more calories after exercise has halted .
As we mentioned earlier, insulin sensitivity also plays a role in the development of skinny fat. Insulin resistance is a trigger for your body to store fat. GLUT-4, an insulin responsive glucose transporter and a marker of insulin sensitivity, is found primarily within adipose tissue and muscle. When there isn’t enough insulin to transport glucose into cells or insulin isn’t working properly to allow it in, it remains in the bloodstream. When blood glucose levels are excessively high, this can be a precursor to metabolic syndrome. One of the most common symptoms seen with metabolic syndrome is central obesity.
Many studies have been conducted on the effect of exercise on GLUT4 levels. One study showed that two weeks of interval training in people with type II diabetes decreased blood glucose levels by 13% 48-72 hours after exercise and increased GLUT4 by a whopping 369% . Several other studies show that GLUT4 expression in skeletal muscle and adipocytes is upregulated in response to exercise .
If you’re trying to decrease body fat levels, incorporating daily high-intensity interval training, in addition to resistance training, is a great way to burn body fat and increase overall health.
2. Eat a nutrient dense diet
If you’re regularly hitting the gym and you’re still skinny fat, your diet is likely the culprit — you’re sabotaging your progress with poor nutrition. The body needs certain nutrients to function optimally, so if you’re consuming a diet high in refined carbohydrates and high omega-6 seed oils you’re not giving you body what it needs.
Instead, focus on consuming a nutrient-dense diet. Some of the most nutrient dense foods are animal sources. Here are some great options.
Animal foods like red meat contains a lot of carnitine, an amino acid helping shuttle long-chain fats into our mitochondria to produce life-giving energy (ATP). One meta-analysis that looked at nine studies concluded that supplementing with carnitine led to a greater amount of weight loss and larger drop in BMI compared to a control group that lacked supplementation . As well, another study showed that increasing muscle carnitine levels helped to prevent fat gain by increasing fat burning and energy expenditure during physical activity .
Studies show that muscle carnitine can be increased through dietary carnitine supplementation . However, we can absorb all the carnitine we need from high-quality animal protein if you make sure you get enough of it on a daily basis.
3. Improve your sleep quality
Getting your sleep schedule in check is not only important for regulating body fat levels, but for pretty much every other function in the body. However, if you’re trying to balance out body composition, ensuring proper sleep is critical.
Good sleep has four pillars to it.
- Duration (aim for 7 – 9 hours)
- Quality/depth (going through the proper brain wave cycles)
- Continuity (waking up multiple times per night isn’t good)
- Regularity (going to bed and waking up at the same times is good)
When we sleep, our body releases three hormones that are critically important to growth: human growth hormone (hGH), prolactin, and cortisol. Research shows that up to 70% of hGH secretion occurs during sleep Stage 3, which contributes to muscle growth . Additionally, testosterone levels are also significantly affected by sleep, or lack of sleep. While men naturally have higher levels of testosterone, levels increase during exercise in both men and women. This boost is needed to stimulate muscle development. One study showed a decrease in testosterone levels of 10-15% when sleep was restricted from 9 hours to 5 hours, which was also associated with low energy and increased cortisol levels .
If you’re having difficulty sleeping, try incorporating Dr.Kirk Parsely’s sleep targeted supplement (especially for sleep onset). Alternatively, if you struggle with shutting your mind off, try breathing exercises and/or meditation to calm the body down prior to sleep. We recommend Sam Harris’ Waking Up meditation app and Wim Hof’s breathwork practice.
There’s also this technique from Bill Starr’s classic book, The Strongest Shall Survive:
- Inhale deeply through the nose — as close to 100% as possible
- When you cannot inhale anymore, take one last inhale
- Hold this for 5-10 seconds
- Exhale 100% through pursed lips
- When you think have fully exhaled, force one last exhale
- Hold for 5-10 seconds
Skinny fat isn’t really a new concept but it’s something that most people take lightly or fail to notice about themselves. Despite appearing perfectly normal, being skinny fat poses a serious health risk. You can get from a skinny fat body to a healthier body composition through healthy lifestyle changes we outlined, such as a well-formulated ketogenic diet, regular resistance training and good sleep hygiene.
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Written by Raphael Sirtoli, MSc, Ph.D. (candidate)
Raphael Sirtoli has an MSc in Molecular Biology and is a Ph.D. candidate in Neuroscience at the Behavioral n’ Molecular Lab in Portugal. His understanding of metabolism, nutrition and clinical medicine is the base upon which Nutrita’s knowledge derives from. He loves open scientific debate, Crossfit, football, hiking, and cold water immersion.
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