Introduction
"Would eating as little as possible help you shed pounds faster?"
This question crosses many people’s minds when embarking on a weight loss journey.
However, institutions like the National Institutes of Health (NIH) recommend creating a balanced calorie deficit(500~1000kcal deficit) rather than drastically cutting calories.
Eating too little doesn’t necessarily mean faster weight loss and may lead to significant downsides.
Let’s explore why this is the case.
1. Risk of Muscle Loss
Drastically cutting calories often leads to muscle loss along with fat loss.
Weinsier et al. (1995) in their research, "Body Composition Changes with Weight Loss: Effects of Very Low-Calorie Diets," noted that individuals on VLCDs lost 3 times more muscle mass than those on moderate-calorie deficits, even when both groups lost comparable amounts of weight. This highlighted the disproportionate impact of VLCDs on muscle tissue compared to fat loss.
Similarly, a study conducted by Barbaridou et al. (2001) titled "The Effect of Severe Energy Restriction on Lean Mass in Obese Patients" revealed that participants consuming a VLCD of less than 800 kcal/day experienced significant losses in lean body mass, constituting up to 25% of total weight loss over a 12-week period. This was attributed to the body breaking down muscle tissue to compensate for insufficient energy intake, particularly when protein and resistance training were not part of the regimen.
2. Risk of Weight Regain
Rapid weight loss from severe calorie restriction often results in weight regain over time.
In the study "Adaptive Thermogenesis in Humans," Dulloo et al. (2002) explained that extreme calorie deficits lead to a phenomenon called "adaptive thermogenesis," where the body conserves energy during starvation-like conditions. This metabolic adaptation slows metabolism and increases hunger hormones, significantly increasing the likelihood of weight regain when normal eating resumes.
Similarly, Weinsier et al. (1995) in their research, "Long-term Weight Maintenance in Very Low-Calorie Diets," revealed that individuals on very low-calorie diets (VLCDs, <800 kcal/day) lost weight quickly but regained a significant portion within a year. The study highlights the challenges of sustaining weight loss achieved through extreme calorie restriction.
3. Health Risks
Extreme calorie deficits can lead to various health complications.
According to the 2018 Korean Society for the Study of Obesity (KSSO) guidelines in their publication, "2018 Guidelines for the Management of Obesity in Korea," VLCDs can cause nutritional deficiencies, gallstones, fatigue, and a weakened immune system. Long-term adherence to such diets without medical supervision is not recommended.
Similarly, Franz et al. (2007) in their paper, "Weight Loss Outcomes: A Systematic Review and Meta-Analysis of Randomized Trials," emphasized that maintaining balanced nutrient intake is critical for overall health during weight loss. Severe calorie cuts often lack essential vitamins and minerals, jeopardizing long-term well-being.
4. Decreased Basal Metabolic Rate (BMR)
Extreme calorie deficits can reduce your basal metabolic rate, making it harder to sustain weight loss.
Müller et al. (2015) in their study, "Metabolic Adaptations to Caloric Restriction," showed that extreme dieting often results in metabolic adaptation, where the body burns fewer calories at rest to conserve energy. This slowdown in metabolism can persist even after resuming a normal diet, leading to a vicious cycle of dieting and weight regain.
A 2016 study on participants from the "Biggest Loser" competition, "Persistent Metabolic Adaptation 6 Years After 'The Biggest Loser' Competition," demonstrated that many participants experienced a long-term drop in BMR due to the severe calorie restrictions they endured.
Conclusion
Instead of opting for an extreme calorie deficit, a sustainable approach is key.
Experts, including the NIH and the KSSO, recommend a calorie deficit of 500–1000 kcal/day, which typically results in a healthy weight loss of 0.5–1 kg per week.
Calculate your basal metabolic rate (BMR) and total daily energy expenditure (TDEE), then subtract 500–1000 kcal to create a sustainable calorie deficit.
This method ensures fat loss while minimizing the risks of muscle loss, weight regain, and health complications.
References
Body Composition Changes with Weight Loss: Effects of Very Low-Calorie Diets
The Effect of Severe Energy Restriction on Lean Mass in Obese Patients