Why some people never gain weight

Image Credit: Pixabay

Some people are lucky. They binge on pizzas, burgers, ice creams, fries and chocolates, but don’t seem to add an inch to their waistlines. And we wonder why they never put on weight. It’s genetics, they say. True, their genes gives them high metabolism.

That’s only partly the truth. The other part is perception. We only see them wolf down high-calorie food, but we don’t know what they do during the rest of the day. Maybe they have only one or two meals a day so that the calorie intake evens out. They could have an active lifestyle to burn the calories: they may be playing a sport regularly or at least going for long walks.

People with certain health conditions like hyperthyroidism and diabetes don’t pile on the pounds. Eating disorders such as bulimia and anorexia too can prevent people from gaining weight. So weight management is more than just genetics and portion control.

Weight gain and weight loss: What science says

Genetics: Does it decide your body weight?

Genetics plays a major role in managing body weight since it influences metabolic rate and hormone sensitivity, allowing some people to burn calories faster than others. It also may make them less sensitive to food cues, making it easy for them to resist cravings. But genetics is not the only reason why some people stay slim no matter what they eat.

There’s no evidence that some people are born to burn more calories than others, Dr Ines Barroso, a researcher at the University of Cambridge in England, says, although researchers have identified over 250 different regions of DNA associated with obesity. In a 2019 study published in PLOS Genetics, thin participants were found to have fewer genes associated with obesity. But Barroso, a co-author on the study, says genes alone don’t determine your weight. “We didn’t find genes that were exclusively either protecting from obesity or predisposing someone to obesity.”

Kathleen Melanson, a professor of nutrition and food sciences at the University of Rhode Island, US, concurs. “Our tendency to gain weight or maintain our weight isn’t pre-determined, but it’s also not entirely under our control. There’s genetic, nutritional, and even behavioral factors involved,” she told Live Science.

Starvation hormone: How does it work?

Leptin is a hormone that helps in regulating appetite. People with higher leptin sensitivity tend to control cravings better. An absence of leptin or leptin resistance [when the body doesn’t respond to the brain signals.] can lead to uncontrolled feeding and weight gain. So people with leptin deficiency can be obese.

Known as starvation hormone, leptin is a protein that tells the brain if there’s enough energy stored in fat cells to carry out normal metabolic processes required to maintain the body. When leptin levels are above a certain threshold [higher sensitivity], the body burns energy at a normal rate, but when it dips, the body conserves energy and stimulates hunger pangs.

The thinness gene

Researchers at the University of British Columbia have identified a gene called Anaplastic Lymphoma Kinase (ALK) which they say plays a role in resisting weight gain. Dr. Josef Penninger and his team reported the discovery of a mutation in the ALK gene in a thin group of people in a study published in the journal Cell.

The gene is known to mutate frequently in several types of cancer, driving the development of tumours. “ALK acts in the brain, where it regulates metabolism by integrating and controlling energy expenditure,” says Michael Orthofer, the study’s lead author and a post-doctoral fellow at the Institute of Molecular Biology in Vienna.

Digestive enzyme: How it regulates body fat

MGAT2 (monoacylglycerol acyltransferase-2) is a digestive enzyme that regulates fat in the body. So if the enzyme is absent and the body will be unable to use fat, helping them to stay thin. Scientists at the University of California in San Francisco found that mice without the gene for MGAT2 can eat whatever they want without getting fat. The results suggest that the enzyme has a pivotal role in lipid metabolism in the small intestine, and curbing MGAT2 can help in the treatment of obesity-related metabolic disorders, according to a journal published by the US National Institutes of Health’s National Library of Medicine.

Basal metabolic rate: How it influences calorie spend

Basal metabolic rate is the minimal rate of energy burned per unit time by the body when it’s at rest. This energy is spent on normal metabolic processes like breathing, pumping of the heart, and functioning of brain. So people with high basal metabolic rate expend more calories at rest and they don’t gain weight easily. The rate decreases as a person grows older and it increases when there’s a spike in muscle mass.

Food choices: How it affects body weight

Weight gain is intrinsically linked to the quantity and quality of food consumed. If people eat large quantities of food that’s less nutritious and low in calories, they won’t gain weight. High sugar and highly processed food will have alarming levels of calories that will increase a person’s weight. So the right amount of nutritious food is the key.

You don’t have to hit the gym regularly, moving around a lot is good enough. Even non-conventional exercises results in calorie burn over an extended period.
Image Credit: Pixabay

Physical activity: Why it’s important

An active lifestyle makes a huge difference. You don’t have to hit the gym regularly, moving around a lot is good enough. Some people are predisposed to moving more and that extra movement can burn a lot of calories even though it’s not a workout. Even non-conventional exercises results in calorie burn over an extended period.

Non- conventional exercises: What are they?

Non-exercise activity thermogenesis (NEAT) is an efficient way to manage body weight. NEAT constitutes body movements that do not qualify as exercise but can help expend calories. Walking around while talking over the phone, any kind of physical labour like cooking or cleaning, walking a dog, using a standing desk, climbing stairs, and fidgeting are some of them. It’s also called non-exercise physical activity (NEPA). NEAT increases the metabolic rate, leading to a substantial energy loss over a long period.

Appetite regulatory system: How food intake is regulated

The nervous system and hormones in the blood interact to signal when a person is hungry or full. This is called the appetite regulatory system. When energy stores in the body are depleted, a stimulus for appetite will trigger the start of feeding, and it’s counterbalanced by satiety, the opposite stimulus to stop eating.

Sleep: Why it’s very important

The hormone cortisol plays a vital role in regulating hunger. So sleep deprivation sleep leads to stimulation of cortisol resulting in weight gain.

Skinny fat: The dangers that lie beneath

Skinny fat is medically known as metabolically obese but within a normal weight range for the height. It’s a phrase used to describe people who look fit and healthy, but suffer from a range of health problems due to a lack of exercise or poor diet. These people can have the same diagnostic markers of diabetic patients like high blood sugar, low good cholesterol, high triglycerides, inflammation, and high blood pressure. They can also have vitamin deficiencies, resulting in fatigue and poor levels of concentration.

Underweight: It’s as dangerous as obesity

If a person’s BMI is below 18.5, he or she is said to be underweight. That body mass is not enough to sustain optimal health. According to studies quoted by Healthline, being underweight can raise the risk of early death in men by 140 per cent in men, and by 100 per cent in women. It can also decrease immunity, increase chances of infections, osteoporosis and fractures, besides causing fertility problems.

People suffering from bulimia eat frequently, consuming a huge amount of food high in calories without even tasting it. They feel out of control. (Picture for illustrative purpose)
Image Credit: Pixabay

Eating disorders prevent weight gain and impact health

Eating disorders are medical conditions that adversely impact health. An excessive focus on body weight results in dangerous eating behaviours that deprive body of nutrition. This can affect the heart, digestive system and other organs, and trigger major diseases. The most common eating disorders are anorexia nervosa, bulimia nervosa and binge-eating disorder.

Anorexia nervosa

People suffering from anorexia nervosa have an excessive fear of gaining weight, even if they are severely underweight. So they may restrict their food intake or compensate it through various purging behaviours like forced vomiting or use of laxatives. Some others exercise obsessively to shed weight. Over time, the body may go into starvation and they could slip into depression.

Bulimia nervosa

This binge-eating disorder can go unnoticed as the patients may not be thin. These people eat frequently, gorging a huge amount of food high in calories without even tasting it. They feel out of control. Stomach pains and the fear of weight gain force them to vomit, use laxatives or exercise excessively. The frequency of such bouts are alarming.

Binge-eating disorder

It’s similar to bulimia as patients consume huge amounts of high-calorie food in a short period. The crucial difference is that people with binge eating disorder do not employ purging behaviours to compensate for their binges.

Restrictive food intake

Avoidant/restrictive food intake disorder (ARFID) causes people to eat very less due to a lack of interest in food or an intense distaste for certain foods. This can lead insufficient calorie intake and the lack of nutrition could result in poor development of the body in youngsters.

How some health conditions affect body weight?

Weight loss can be a sign of illness. Some health conditions like hyperthyroidism and diabetes can cause unintentional weight loss. It could also be triggered by cancer, depression, certain infections, bowel diseases among many other ailments.


Hyperthyroidism occurs when the thyroid gland produces excessive thyroxine (a hormone). Mostly seen in women, an overactive thyroid accelerates body’s metabolism, causing unintentional weight loss and a rapid or irregular heartbeat, according to Mayo Clinic.


In people with diabetes, the body fails to produce enough insulin to process the sugar in the bloodstream. So, the body starts burning fat and muscle for energy, causing a reduction in overall body weight.

Real life stories: How some people continue to remain thin

Samir Salama: Food and lifestyle have helped me stay slim

I have always had a body mass index (BMI) of less than 20. [BMI is weight in kilograms divided by the square of height in metres. A BMI of 18.5 – 24.9 is considered normal or healthy]. I am in good health, and have no medical conditions or eating disorders. My lifestyle plays a major role [in maintaining my weight], Samir Salama, Gulf News Associate Editor based in Abu Dhabi, says.

Genetics does play an important role in determining the body weight. My parents and siblings too are like me. They too don’t gain weight easily.

I increased the fibre in my diet, which helps make me feel full…I always get outside and move quite a bit…My daily fluid intake has been increased to at least three litres. I also ensure that I get enough sleep.

– Samir Salama

Besides genetics, there are other things too. To stay in shape, one has to exercise. It doesn’t have to be strenuous activity. When I was young, I used to walk to and from school 15kms a day, and enjoyed working in the field with my grandfather in Egypt. I have been eating a lot of herbs, which we grew ourselves, and many meals are eaten outdoors, or in the fields.

So when I moved to the UAE, I increased the fibre in my diet, which helps make me feel full and is beneficial to the microbiome in the gut. It has an impact on body weight too. In the UAE, my outdoor activities are not the same [as in Egypt]. I don’t have the luxury of a garden, but I always get outside and move quite a bit (non-conventional exercise), which is very important. My daily fluid intake has been increased to at least three litres. I also ensure that I get enough sleep, which can impact appetite and metabolism.

I believe sustainable weight loss is a marathon not a sprint. It doesn’t do any good if you lose 20kg, then gain it six months later. A good food regimen should be for life, and parents should recommend it to their children.

Mohammad Al Jashi: I tried to put on weight, and failed

People have always been in awe of my metabolism. No matter how much I eat, I can never gain weight, Mohammad Al Jashi, a freelance writer based in Toronto, Canada, says.

I was always fascinated by how quickly my friends put on weight. They end up adopting a stringent dietary regime of salads and no carbohydrates, something I could never wrap my head around since potatoes (crisps) and rice are a daily staples of my nourishment.

I would eat around five to six meals a day for over three months, resulting in the addition of 5.5kg. It was infuriating, because eating became a chore, and meals were no longer enjoyable…

– Mohammad Al Jashi

At 57kg, I’m very conscious about my lanky physique. I have tried to put on weight. There is one attempt that sticks out in particular: My skinny cousin suggested an appetite stimulant that worked wonders. I became hungry always and my portions grew even larger in size. I still remember how famished I used to be in the morning, to the extent that I would prepare my breakfast before even considering washing my face. It felt like my appetite could never be sated.

I would eat around five to six meals a day for over three months, resulting in the addition of 5.5kg. It was infuriating, because eating became a chore, and meals were no longer enjoyable as it became a means to tamp down the painful rumblings of my tummy.

Then Ramadan rolled along. Once it was over, I hopped onto the scale to find out that I lost my record gain of 5.5kgs. I realised that this is something beyond my control.

To me, gaining weight is difficult, but for my friends weight loss is a commitment that requires plenty of self-control and discipline.

Image Credit: Seyyed Llata, Senior Designer

Staying healthy: What the experts say

Suchitra Bajpai Chaudhary, Senior Reporter

While most of us are huffing and puffing on the treadmill, counting calories and resisting our favourite foods, we have some people seem to have their cake and eat it too. In other words, these people not only eat well, but they also don’t need to watch the scales. How do they achieve this impossible feat?

Gulf News spoke to a nutritionist, a gastrointestinal specialist and weight loss expert to learn what revs our metabolism. They pin it down to three main factors: behavioural patterns, sound nutrition and genetics.

Dr Fiona Cowie, Weight loss expert

Dr Fiona Cowie, an aesthetician with a certification in advanced weight loss management at the Dermalase Clinic, Jumeirah, Dubai, said weight loss and super-charged metabolism in many people could be due to NEAT. “This is Non-Exercise Activity Related Thermogenesis. Some people may not be going to the gym but have an active lifestyle. From cooking, cleaning, looking after the kids, pacing in the office to even fidgeting with a pen, their activity levels can be high, leading to a constant calorie burn. It is estimated that NEAT can boost metabolism up to 50 per cent. Many people might go to the gym but overall follow a sedentary lifestyle.”

Two other significant factors are sleep and eating pattern. “Our nervous system and our hormones together work in tandem to create an appetite regulatory system. When people don’t have good eight hours of sleep at night, it triggers cortisol release because of the stress. This activates the ‘hunger hormone’ leptin, and they tend to snack a lot and put on weight. Others just have a huge appetite and tend to eat even when they are not hungry. Those with great metabolism are those who sleep well and eat only when hungry,” Dr Cowie added.

Mitun De Sarkar, Clinical dietician

Mitun De Sarkar, a clinical dietician with Simply Healthy, Dubai, attributed to the slender physique of some people to mindful eating. “While we might see many people eating heavy food, we are not privy to their total eating pattern. These people are likely to balance out their calories for the day. Therefore, even if you saw them eating and drinking at one particular time, they might be eating a light dinner or completely cutting out on snacking. This is behavioural. They are mindful of this behaviour and know how to compensate off the excess calories later.”

According to Dr Rajesh Nambiar, specialist gastrointestinal (GI) surgeon from the International Modern Hospital, Dubai, some people are blessed with a good Basal Metabolism Rate (BMR), which helps them burn calories at a faster rate without activity. Of course, BMR can change according to one’s lifestyle. However, it is a proven fact that a higher BMR can boost metabolism by up to 15 per cent. “

Dr Rajesh Nambiar, Specialist gastrointestinal surgeon

The length of the gut matters a lot. “The small intestine is the site where nutrition from food gets assimilated. The small intestine length can vary from 120-180 cm and in taller people; it is usually longer compared to those who are shorter. Taller people tend to have more lean muscle mass and better BMR that allows them to eat and also burn calories faster,” Dr Nambiar added.

Other factors that can provide a robust metabolism is regular physical exercise and an active lifestyle. “Physical activity, in general, can make a big difference. People who are up and about, always on the move, not necessarily gym freaks but with an active job or new mums chasing their toddlers and busy with household chores, are able to keep their weight off even while snacking around. All these movements rev up the metabolism, increasing the number and activity of mitochondria in the cells. More the mitochondria in your muscles higher the basal metabolic rate of your body,” De Sarkar said.

But big eaters who are skinny must check their body composition. “If the analysis reveals a higher body fat percentage, high cholesterol and triglyceride levels, it is advisable to cut back on incessant eating and watch what they eat to avoid serious health repercussions,” De Sarkar added.

Fill up half of your plates with nutrient-dense, high fibre, colourful vegetables.
Image Credit: Pixabay

10 tips to manage your weight

Dona Cherian, Assistant Online Editor

Farah Hillou, Integrative and functional nutritionist

Farah Hillou (MS, RD, IFNCP), Integrative and Functional Nutritionist at Chiron Clinic in Dubai gave Gulf News her top ten tips to prevent unhealthy weight gain.

1. Restrict the eating window

Practise time-restricted feeding for at least 14 hours a day. Research has shown that practising time restricted feeding and intermittent fasting can help reduce inflammation, control blood cholesterol and insulin levels, promote autophagy, boost brain health, and help maintain a healthy weight. For instance, dinner can be at 7pm while breakfast the next day is around 9am.

2. Limit snacking

Not only does this prevent grazing and taking in more foods than necessary, but it supports the MMC (migrating motor complex) which optimises digestion.

3. What you eat is crucial

Fill up half of your plates with nutrient-dense, high fibre, colourful vegetables. Include greens like spinach, kale and arugula, as well as cruciferous vegetables like cabbage, broccoli and cauliflower. Add vegetables to your smoothies, soups, and stews.

4. Satiety with proteins and fats

Include protein and/or healthy fats at every meal. This can help with satiety (feeling full) and promotes blood sugar balance. Protein foods include meat, fish, beans, lentils and quinoa while healthy fats include nuts, seeds and avocado.

Avoid foods high in sugar such as cakes, cookies and pastries. Excess sugar can be stored as excess body fat.

5. Support your gut

Studies have shown that an imbalance in gut microbes can stimulate weight gain over time. Add 1 tablespoon of probiotic-rich fermented vegetables such as sauerkraut and kimchi to your meals every day. Moreover, eat prebiotic foods such as garlic and onions to boost healthy gut microbes.

6. Mindful eating

Practise mindful eating by starting with three deep breaths before eating, chewing slowly, and placing your fork down between every few bites. Apply the Japanese proverb “Hara Hachi Bu”: eat until you are 80 per cent full.

7. Read the labels

Refer to the nutrition facts table and the ingredient list whenever your purchase any packaged foods. Ingredients are listed in order of weight, let go of anything with ingredients you cannot pronounce, and those that have sugar listed in the top few ingredients.

8. Meal planning to deal with cravings

Plan your meals ahead of time and batch cook on weekends. Sudden hunger pangs can have you reach out for anything in sight.

9. Sleep on time

Follow your circadian rhythm and sleep on time; aim to go to bed at 10pm and get 7-8 hours of sleep. Poor sleeping habits can help pile on those extra pounds.

10. Meet an expert

If you are struggling to maintain a desirable weight despite feeling like you are doing everything right, it is important to consider factors such as stress, insulin resistance and hormone imbalances, food sensitivities and exposures to toxins. Working with a Functional Medicine practitioner can help you get to the root cause of any imbalances.

Leave a Reply

Your email address will not be published. Required fields are marked *