Weight Cycling and the Microbiome
Do you feel like your dieting efforts are like a merry-go-round that you can’t get off? You diet, you lose weight, you struggle to stay within the confines of the diet, you break the diet, you gain back the weight, and “start all over again.” Yo-yo dieting, or weight cycling, describes the dieting and frustrating weight regain that we often experience. Some reasons why we can’t seem to maintain weight loss long-term includes the constant availability of food, the gargantuan portions we face daily, the connection between socializing and food, the prevalence of unhealthy, high calorie food, and the fact that when we lose weight, we really need less food to support our smaller mass – but we can’t seem to sustain that lower calorie level. Research now suggest that our weight regain may have something to do with the type of microbes that persist in our gut even after significant weight loss.
It’s not only a fact that most of us regain the weight after a good run of dieting, but the weight regain occurs pretty quickly. We often gain back even more than we lost. This rebound weight loss has been the subject of much scrutiny by scientists. If we can figure out a prominent cause, science should be able to figure out new therapies to intercept it. Obesity rates among children, teens, and adults are at an all-time high, and the incentive to reverse the trend is crucial to also reducing rates of comorbid diseases like diabetes, heart disease, and several cancers.
Using Mouse Models to Study the Yo-yo Effect
The original research published in the 2016 journal Nature, has been revisited because of a growing focus on the gut microbiome. Our stomach and intestinal tract are filled with bacteria (microbes) and the balance of the different categories of these microbes depends on a number of factors. It also affects many of our bodies processes. Researchers at the Weizmann Institute of Science in Israel used mouse models to investigate the cause of the yo-yo weight phenomenon.
The most notable finding of the study was that when obese mice gain and lose weight, many of the body’s systems and organ functions revert to a normal baseline – except for the microbiome. The microbiome seems to retain a “memory” of the obese period and it contributes significantly to and accelerates regain of weight, especially when the mice start to eat normal or excess amounts of food after a dieting phase. That means the deck is pretty much stacked against maintaining weight loss.
Mice were put on a diet and researchers monitored their gut microbiome. For about six months after weight loss, the mice had an abnormal obesogenic (weight-promoting) microbiome. So, despite other parameters like cholesterol and blood sugar normalizing, microbes in the gut still stayed the same. In one experiment, the mice were given a hefty dose of antibiotics, the obese microbiome was disrupted and destroyed and weight gain was halted. In another experiment, the obese-prone microbiome from obese mice was introduced into mice bred with no microbiome, and as soon as the mice were fed extra calories in their diet, weight gain was dramatically accelerated.
Models Predict Weight Loss Trends
The researchers concluded that the microbiome plays a significant role in supporting weight loss (or gain) and metabolic function. If the obese-prone microbes persist after weight loss, then even after a phase of successful dieting, it seems almost inevitable that there will be faster weight regain and metabolic aberrations as soon as a person with a past history of obesity is exposed to even just a small increase in calories.
The researchers were also able to plug data from their study into an algorithm that pretty closely predicted “how much weight” each mouse would regain. They then identified two molecules that seemed to drive the impact of the microbiome on weight regain. The molecules, from a class of compounds called flavonoids, seemed to degrade during the weight loss process. So, their levels are quite low once substantial weight is lost. Levels of the two flavonoids also seem to be lower in obese mice compared to mice that have never carried excess weight.
Low levels of these two flavonoids seem to impair energy burning which means calories consumed would not be effectively utilized by the body (hence, weight gain). So, you eat more than you should after losing weight, and you don’t burn the calories efficiently – a surefire way to regain weight quickly – if this research model is correct. When the researchers supplemented the mice diets daily with flavonoids mixed in a beverage, the weight regain slowed substantially and the mice did not experience “accelerated” weight regain.
Adding More Flavonoids to Your Diet
Using flavonoid supplementation is quite different from other approaches to restore gut microbe balance or change gut microbes. Probiotics – the introduction of the actual microbes – is a pretty popular approach to restore gut health. In this experiment, the approach was to use specific molecules to change and improve the gut population- and not to simply supplement with the actual microbes. Let’s remember, though, this was a mouse study, so it will take additional research to see if the theory holds for humans.
If you’re curious as to which foods are high in flavonoids, they include:
Apples (with the skin on)
Very dark chocolate
Notice a theme here? The very foods you should be including in a balanced diet, and the very foods that should replace high fat, high calorie, highly processed foods, are foods high in flavonoids. One of my biggest gripes, as a nutritionist, is the idea of just going “lower calorie” for weight loss, an approach that often neglects the quality of food. A person could conceivably eat fast food and just reduce calories dramatically and lose weight. The research seems to suggest that the “type of calorie” may count – a lot – if you are trying to sustain weight loss.
Until this research pans out to apply to humans, some tips to lose weight and keep it off:
Choose a diet that nutrition experts endorse like the DASH or Mediterranean diet, but personalize it to your needs
Get the help of a dietitian or nutritionist to determine how many calories you should eat daily to achieve safe, steady weight loss
Consider reducing the number of servings of grain carbohydrates and choose whole grains and high fiber grain choices that are minimally processed
Meet daily goals of water hydration
Embrace daily exercise and include aerobic (calorie burning) and weight training to maintain and build muscle mass
Create a home and work environment that supports sustained weight loss (do not bring in temptations)
Use a support buddy or group
Learn ways to manage cravings – keep a hot low-calorie beverage nearby, chew gum, get up and move around when tempted
Be mindful that obesity is a chronic disease that requires ongoing management