Is Undereating After Bariatric Surgery Causing Weight Loss Resistance?

Bariatric surgery is often regarded as a life-changing procedure for those who struggle with obesity. There is no doubt that it can lead to significant weight loss, but it does not come without its challenges. One lesser-known obstacle many post-bariatric patients face is the belief that undereating leads to sustained weight loss. 

In this article, we will discuss how chronically eating too few calories can slow down metabolism, impeding weight loss efforts. Let’s investigate the science behind it and understand why undereating might not be the solution.

The Metabolism Mystery

Our body’s metabolism is made up of a complex interplay of biochemical processes that burn calories to produce energy. In order to lose weight, it is imperative to keep in mind that a calorie deficit is indeed beneficial. The key is to consume enough calories to support your body’s functions without adversely affecting your metabolism.

Undereating Defined

Deficiencies of dietary calories are not simply a matter of consuming fewer calories. Rather, undereating refers to the chronic restriction of calorie intake to levels below the body’s requirements for essential functions and daily activities. In the context of post-bariatric surgery, undereating typically involves chronic calorie consumption between 1000-1200 a day. 

There is a common misconception among bariatric patients that further reducing calorie intake will accelerate their weight loss. The problem with this misconception is that it often results in weight loss resistance and other health problems. There are several factors that contribute to bariatric patients’ undereating:

Initial Post-Surgery Eating Restrictions: 

A strict diet is often prescribed immediately following bariatric surgery, with solid foods gradually introduced. The cautious approach minimizes the risk of complications and ensures proper healing of the surgical site. A short-term diet restriction, however, can often lead to long-term eating habits that are undernourished.

Fear of Weight Regain: 

It is common for bariatric patients to be frustrated by their previous attempts to lose weight due to obesity. In turn, they may develop a deep-seated fear that they’ll regain the weight they’ve lost. A fear of gaining weight can lead to a determination to restrict calories further to prevent it.

Physical Discomfort: 

Certain foods and larger portions may cause discomfort after bariatric surgery because of altered digestive processes. Due to this discomfort, we tend to consume fewer portions of food, inadvertently resulting in undereating.

Misconceptions About Caloric Intake: 

There is a common misconception among bariatric patients that reducing calories further will prevent weight regain. Undereating can be perpetuated by this misunderstanding since patients believe strict calorie restriction will maintain weight loss.

Metabolism and the Imperative of Caloric Sufficiency

In the human body, metabolism refers to a series of chemical reactions that are responsible for maintaining life by converting food into energy that is required for vital bodily functions such as respiration, digestion, and physical activity. The impact of undereating on metabolism can be summed up in two key ways:

Slowing of Metabolism: 

An extended period of low-calorie consumption gives the body the impression that energy is scarce, triggering a metabolic response that conserves energy. An adaptation to this situation, often referred to as entering “starvation mode,” reduces energy expenditure significantly.

According to studies, when the consumption of calories is consistently low, the body reduces energy expenditure to conserve resources. As a species, we have adapted to this survival mechanism over the course of evolution. As a result of energy conservation, the body burns fewer calories at rest and while exercising.

Metabolic Adaptation: 

As a result of prolonged caloric restriction, the body becomes more efficient at utilizing the limited energy it has at its disposal. Consequently, weight loss efforts are hindered because fewer calories are expended during day-to-day activities.

According to research, chronic under-eating triggers the body to become more efficient in using the limited calories it receives by enabling the body to utilize the calories at a higher rate. As a result of this higher efficiency, fewer calories are expended during daily activities, making calorie deficits harder to achieve.

Factors triggering metabolic slowdown from undereating

The following factors contribute to metabolic slowdown:

1. Adaptive Thermogenesis: 

One key aspect of the metabolic impact of under-eating is a process called adaptive thermogenesis. The ability of the body to adjust its metabolic rate in response to changes in calorie intake is know as adaptive thermogenesis. Your body perceives too few calories as a threat to its energy balance when you consistently consume too few calories. Thus, adaptive thermogenesis is initiate to conserve energy. Among other things, this also includes reducing the speed at which your body burns calories at rest, also known as resting metabolic rate (RMR).

Several studies have shown that prolonged calorie restriction decreases RMR. One classic example is the Minnesota Starvation Experiment which took place during World War II. In severe calorie-restricted diets, researchers observed that subjects’ metabolic rates dropped significantly to preserve energy.

2. Hormonal Changes: 

It is also important to note that chronic under-eating leads to a change in the hormonal profile, and this leads to a metabolic slowdown. The hormone leptin produced by fat cells plays a crucial role in energy balance and metabolism. When you consume too few calories, your fat stores decrease, reducing leptin levels. A low level of leptin signals to the brain that the body is in a state of energy deprivation, which triggers energy conservation mechanisms.

There have been numerous studies showing that leptin affects metabolism. In response to calorie restriction, leptin levels decrease, which affects energy expenditure and appetite. As a result of this hormonal shift, the body slows down its metabolism and increases hunger, making weight loss even more difficult.

3. Loss of Lean Body Mass: 

Chronic under-eating can also lead to the loss of muscle tissue. The amount of lean body mass you have affects your metabolic rate at rest, so as your muscle mass decreases, your metabolism slows further.

A lack of protein intake can result in muscle loss as a result of calorie restriction. The loss of muscle contributes to a decrease in RMR. Researchers demonstrated that calorie restriction without adequate protein consumption results in a reduction in lean body mass and metabolic rate in a study.

The Bariatric Patient’s Dilemma that contributes to undereating

Many post-bariatric patients are finding themselves in a predicament where they have lost weight after surgery but cannot maintain it or have even gained it back. Their response may be to cut their caloric intake further, believing that this will help them lose weight again. It is unfortunate that this approach often backfires.

Undereating & weight loss resistance

In a study entitled “Metabolic Determinants of Weight Gain in Humans,” researchers investigated the relationship between metabolic factors and weight gain in humans.

Those who are metabolically thrifty are more likely to gain weight than those who are metabolically spendthrift, as their resting metabolic rate is lower and their energy intake is less responsive to changes in energy intake. In addition to burning fewer calories at rest, metabolically thrifty individuals are less likely to increase their calorie expenditure when they overeat.

In addition, the study found that people who are under-eating are more likely to have difficulty losing weight. As a result of under-eating, the body can burn less fat and its resting metabolic rate may decrease.

It is suggest by this study that metabolic factors contribute to weight gain and weight loss resistance. It is more difficult to lose weight for people who are metabolically thrifty and who undereat.

A few of the study’s key findings are as follows for undereating:

Metabolically thrifty individuals are more prone to gain weight in free-living conditions than metabolically spendthrift individuals.

A more significant decrease in 24-hour energy expenditure (EE) during fasting and a more minor increase in 24-hour EE during overfeeding are both features of the metabolic thrifty phenotype and are predictive of weight gain.

Weight loss resistance is more likely to occur in people who under-eat.

As a result of under-eating, the resting metabolic rate and fat-burning ability of the body can decrease.

Understanding Metabolic Adaptations and Appetite During Weight Loss

According to one study, “Metabolic adaptations during negative energy balance and their potential impact on appetite and food intake” examines how metabolic adaptations can affect appetite and food intake during negative energy balance. 

If total energy and protein intake are equalize, sustain negative energy balance results in weight loss and body composition changes that are similar to those in different dietary interventions. 

It is know that when the body is underfed, there are compensatory metabolic and behavioral responses that attenuate the prescribe energy deficit. While losses of metabolically active tissue result in reduce energy expenditure during an energy deficit, additional decreases in expenditure have been observe that cannot be explain by changes in body tissue (e.g. adaptive thermogenesis). 

In the course of weight loss, sustain negative energy balance is associates with an increase in orexigenic drive and changes in appetite-relate peptides that may lead to an increase in food intake and appetite. The loss of fat-free mass (FFM) during weight loss may also act as an orexigenic signal, but there is still a lack of data to support these findings, and the pathways linking FFM and energy intake are unclear. 

The Solution: Proper Nutrition and Metabolic Reset

After bariatric surgery, overcoming weight loss resistance involves providing your body with the necessary nutrition and signaling your metabolism that it is safe to lose excess weight. The following are some essential strategies:

1. Consult a Registered Dietitian: It is important to seek the guidance of a qualified professional who will be able to create a nutrition plan specific to your needs following surgery.
2. Focus on Nutrient-Dense Foods: Choose whole, nutrient-dense foods that will provide your body with the vitamins and minerals that it needs. As a result, nutrient deficiencies resulting from bariatric surgery can be prevent to a greater extent.
3. Protein Intake: As part of maintaining muscle mass and supporting metabolic health, it is important that you meet your protein requirements.
4. Balanced Caloric Intake: Keep track of your caloric intake to ensure you are getting enough energy without slowing down your metabolism in the process.
5. Regular Physical Activity: Adding regular exercise to your routine will help you boost your metabolism and improve your overall health.
6. Adequate Hydration: Keep hydrated to prevent dehydration and support metabolic processes.

Conclusion

When it comes to weight loss after bariatric surgery, under-eating is not the answer.  Rather than focusing on calorie restriction, provide your body with the nutrition it needs. 

Ensure your metabolism remains active and supports your weight loss goals by seeking professional guidance on nutrition and lifestyle. Remember that the key to losing weight is not to eat less; it is to consume the right amount of food.