Reshaping the gut is the secret to successul weight loss

Reshaping the gut is the secret to successful weight-loss

Bhavna Karnani

Bhavna Karnani

After obtaining her MSc in Microbiology and Immunology from ETH Zurich, Bhavna continued her academic experience as a Junior Researcher in Milan to gain a deeper understanding of regulatory T cells involved in cancer and autoimmune diseases. Bhavna currently works in the Scientific Affairs department in Lugano, Switzerland. She strongly believes that adequately educating the public on complex medical and scientific matters is of utmost importance for the progression of our society.

Obesity is on a dangerous rise predominantly in developed countries, to the point where we are currently seeing more lives lost due to being overweight rather than underweight. Even with hundreds of diets out there, we still face challenges when it comes to leading healthy lives. Recent scientific evidence suggests that diets rich in fiber can positively reshape the gut microbiome and help to lose weight in a healthier fashion. Thus, targeting the microbiome for weight control could be the secret to bringing obesity to a standstill in the near future.

The prevalence of malnutrition has been a longstanding global burden in many countries around the world. Nearly 500 million individuals, including children, from low- and middle-income countries such as India, Pakistan, Kenya and China are underweightNevertheless, foods that are high in fat, sugar and salt tend to be cheaper in these countries and are being increasingly consumed. These dietary patterns together with lower levels of physical activity have increased childhood obesity rates, while undernutrition still remains an unsolved burden of diseaseThis interplay of opposing factors has paradoxically brought about more lives lost by being overweight rather than underweight, especially in middle- and high-income countries.

According to the World Health Organization, as of 2016, a staggering 1.9 billion adults aged 18 years and up were overweight, of which 650 million were morbidly obese. Just to give you a global perspective on the severity of the issue, 1.9 billion represents 25% of the entire population on planet Earth. This should be a real eye-opener because evidence has shown that with obesity comes an increased risk of cardiovascular diseases and cancer, which are the leading causes of death in middle- and high-income countries. Obesity is a multifactorial disease, mainly caused by the individual’s diet, but other factors have been scientifically shown to play a large role too, such as genetics, environmental, and societal factors such as urbanization and the increasing sedentary nature of many forms of work leading to a lack of physical activity. While our altered lifestyle patterns have fueled the risk of obesity, so has the importance of dieting to mitigate the problem. What has followed is a swarm of nutritionists and diet gurus from all walks of life, preaching about the ‘miracle diet’ and what they believe is the secret to a perfect and healthy physique. Even as a young girl, I remember frequently seeing weight-loss programs like Nutrisystem, Jenny Craig and the South Beach diet being advertised on television, often promoting to be the fastest and best weight-loss plan. However, as I grow older, the number of diets seem to keep piling up, most likely because people have begun to realize that not all bodies are built the same, so there is no such thing as ‘the perfect diet’. But why is there no such thing as the perfect diet? Scientists have been scratching their heads just as much as we have, and, quite recently, they think they might just have the answer. They are now intervening on this global burden and are telling us to look no further than the gut.

Why is obesity on the rise?

To meet our increasingly hectic lifestyles, food and agricultural industries across the developed world have advanced throughout the years by providing strategies to ensure the availability of food for their consumers whenever and wherever. With the rise of automation, ready-made meals and fast-food chains are increasingly flooding our cities. These types of foods are high in fats, sugars and sodium, which cause hypertension, poor nutrient uptake, slower metabolism and negatively influence the body’s ability to control its glucose levels (1). More specifically, diets high in sugars lead to increased levels of the hormone insulin which can retain sodium (2). Consequently, diets high in sodium increase water retention in the body which then raises the blood pressure (1). The higher the blood pressure, the greater the strain on your heart, kidneys and brain, which are factors that can lead to heart attacks and strokes. While small amounts of fats are essential for our bodies to absorb fat-soluble vitamins like vitamin A, D, E and K, diets high in fat can actually lead to the increase in blood cholesterol levels and a build-up of fat deposits in coronary arteries, which can also cause heart attacks (3). If these eating patterns are not kept in check, they can lead to excessive weight gain and weakening of the immune system, which can give rise to many disorders such as cardiovascular disease, type-2 diabetes and ultimately death. Because these high-fat and high energy foods have been increasingly incorporated into our daily diets, it has led to the alarming rise of obesity that we see across the globe today.

Reshaping the gut is the secret to successul weight loss
Reshaping the gut is the secret to successful weight-loss. Photo @ Pexels.

Why some commercial diets simply don’t work

Naturally, we believe that with every problem comes a simple solution; and, in this case, the solution is believed to be dieting. Whether it’s the Keto, Paleo or Vegan diet (4), all of us, at least once in our lifetime, have probably tried some sort of diet. We are constantly being bombarded by the media, dieticians and the entertainment industry with misinformation wanting us to believe that everyone is capable of losing weight – and fast. We are led to believe that being healthy is directly correlated with having a slim body, so we try everything in our power to achieve this. You all know how it goes: you follow your chosen diet and deprive yourself from either one or more food items such as dairy, meat, sugars, or simply whatever is trending nowadays. In extreme cases, diets can actually do more harm than good for your body, as is the case with the preposterous “Sleeping Beauty Diet”. The Sleeping Beauty Diet encourages individuals to take sedatives when they become hungry, so instead of eating, they will sleep. Scientifically speaking, however, nutritionists claim that sleeping ‘too much’ can actually alter the hormones that regulate your appetite and hunger, all of which could promote weight-gain and obesity rather than weight-lossMoreover, the Sleeping Beauty Diet greatly minimizes physical exercise, which is an important factor in weight-loss.

Obesity has become such a global problem that it has even reached the television screens in the case of the popular American reality show ‘The Biggest Loser’Here, the goal is for contestants to compete with one another through strict diets and rigorous exercise to be the person who loses the most weight by the end of the season.
Apart from the dramatic on-screen struggles they faced, what made the contestant’s journey all the more interesting is what happened to them after the show had ended. Interestingly, the results of a 2016 study illustrated how individuals who had lost a large amount of weight on the show had ended up gaining it all back – sometimes even moreMoreover, the study indicated a decrease in their metabolism that was completely unexpected. These findings suggested that weight is not just affected by your genes, the foods you eat, or how much you exercise .Thus, researchers decided to dig deeper by asking whether there was another reason behind the increasing challenges we face, when it comes to losing weight…

Listen to your gut!

Over the past decade, researchers have begun unearthing the importance of the gut microbiota, or simply, the microorganisms that are collectively present in the human gastrointestinal tract. They have unraveled the specific differences between the gut microbiota of obese and lean people in order to develop a more personalized approach to weight-loss treatments. In fact, it really seems that weight-loss might depend on the individual gut microbiomeBacteria are essential for our well-being: they help us digest foods and are responsible for providing vitamins to our body. Having the right bacteria and their proper quantities are also essential for warding off dangerous bacteria that may be ingested with contaminated foods or passed on by infections. Recent studies performed with human twins showed significant differences in the gut microbiota between the obese twin and the lean oneSimilar results were also observed in mouse studies, which have shown that the amount and type of microbes are highly influenced by the diet and actually play a huge role in weight gain (5). Recently, it has been suggested that high fiber intake could lower obesity rates in humans (5). Once consumed, dietary fibers are fermented in the gut to produce important metabolites such as Short-Chain Fatty Acids (SCFA’s) that regulate metabolism, provide energy for the body and strengthen the immune system. More specifically, scientific evidence suggest that fibers stimulate the growth of diverse types of bacteria, thereby increasing bacterial diversity in the gut, which is essential for vitamin production (6) and degradation of complex carbohydrates, thus rendering the individual prone to a healthier and natural weight-loss regimen (5). On the contrary, diets rich in animal fats not only decrease bacterial diversity and SCFA production in the gut, but also lead to the production of dangerous metabolites during the fermentation process of amino acids found in proteins. These toxic metabolites further promote a pro-inflammatory environment that often increases the risk of colorectal cancers and inflammatory bowel diseases. Another recent study highlighting the importance of fibers to promote a healthy gut profile was published this year by a team of scientists of the Human Nutrition laboratory at ETH Zurich (7). Here, they showed that with the use of prebiotics, a source of non-digestible fibers, they were able to stimulate the growth of beneficial bacteria (8). Increasing these beneficial bacterial strains in the gut is important since they have the ability to reduce the number of pathogenic bacteria and toxic metabolites, which inevitably promotes a healthy gut environment (7, 8).

The take home message

In 2018, a study provided a detailed overview on the human microbiome profile suggesting that the amount and type of bacteria in our gut could contribute to weight gain independently of physical activity or calorie intake. Furthermore, they explained that while 30% of the human gut biodiversity profile is indeed influenced by genetics, the remaining 70% of the biodiversity is influenced by environmental factors including the diet (9). All in all, the numerous studies thus far suggest that individuals should strive for diets that promote a highly diverse gut microbiota. Additionally, they suggest that having too much of the wrong kinds or too little of the right ones may cause weight gain. Whatever diet you choose to implement in your daily routine is up to you, but what remains constant is the fact that there is no such thing as the perfect diet. Rather than partaking in short-term diets that deprive us completely from eating too much or too little of a single or several dietary element(s), we should instead change the focus on building a long-term healthy lifestyle for ourselves, which not to mention, should also include a healthy amount of physical activity. Moreover, the scientific evidence strongly suggests that we should strive to implement a diet that is rich in fiber and scarce in animal fats. As the gut microbiome is modifiable through an altered diet, we should instead focus on targeting the microbiome for weight control interventions. It seems clear that if we want to stay healthy, we simply need to look no further than our gut because at the end of the day, a healthy gut will give you that perfect butt.


Bhavna Karnani



  1. Bahadoran, Z. et al. “Fast Food Pattern and Cardiometabolic Disorders: A Review of Current Studies”, Health Promot Perspect, 2015
  2. Brands, MW. and Manhiani, MM., “Sodium-retaining effect of insulin in diabetes”, Am J Physiol Regul Integr Comp Physiol, 2012
  3. National Research Council (US) Committee on Diet and Health, “Diet and Health: Implications for Reducing Chronic Disease Risk”, 1989
  4. Paoli, A., “Ketogenic Diet for Obesity: Friend or Foe?”, Int J Environ Res Public Health, 2014
  5. Turnbaugh PJ. et al. “An obesity-associated gut microbiome with increased capacity for energy harvest”, Nature, 2006  
  6. LeBlanc, JG. et al. “Bacteria as vitamin suppliers to their host: a gut microbiota perspective”, Curr Opin Biotechnol, 2013
  7. Pagani, D. et al. “Iron-containing micronutrient powders modify the effect of oral antibiotics on the infant gut microbiome and increase post-antibiotic diarrhoea risk: a controlled study in Kenya”, Gut, 2019
  8. Moro, G. et al. “Dosage-related bifidogenic effects of galacto-and fructooligosaccharides in formula-fed term infants”, J Pediatr Gastroenterol Nutr, 2002.
  9. Makki, K. et al. “The impact of Dietary Fiber on Gut Microbiota in Host Health and Disease”, Cell  Host Microbe, 2018 
Received: 03.06.19, Ready: 28.07.19, Editors: SR, RG.


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