Many people worry that losing fat might damage their metabolism, or that their previous dieting efforts have already caused harm. This concern is particularly common among those who have experienced yo-yo dieting—losing weight only to regain it later. However, recent research published in Current Obesity Reports offers a reassuring perspective.

In a review of scientific studies, researchers concluded that these fears are largely unfounded. According to the review, “the overwhelming majority of evidence suggests that weight-cycling (yo-yo effect) is not associated with any adverse effects in body weight, body composition, and metabolic rate.” This aligns with findings from other scientific literature, which also found no evidence of lasting metabolic damage, even in extreme cases like starvation, bodybuilding, or anorexia.

So, what actually happens when you lose fat? The body undergoes temporary metabolic adaptations, such as lower energy expenditure and increased appetite—mechanisms often referred to as “anti-starvation.” But this term is misleading. These same mechanisms are also anti-obesity! As you gain fat, your energy expenditure typically increases, and your appetite decreases, as the body seeks homeostasis, resisting changes in either direction.

If metabolism isn’t the culprit, why do so many people regain lost weight? The answer is straightforward but not always easy to accept: they didn’t make lasting lifestyle changes. Because metabolism is predictable, the lifestyle that led to weight gain in the first place will likely do so again if not altered.

Instead of worrying about your metabolism or hormones, focus on sustainable lifestyle changes:

• Resistance training
• Moderate cardiovascular exercise
• Proper hydration
• Adequate energy intake from food
• Balanced macronutrients (especially ensuring enough protein)
• Micronutrient-rich diet (think “eat the rainbow” with fruits and vegetables)
• Quality sleep
• Daily activity (aim for 6,000+ steps)
• Time spent outdoors in the sun

These habits should be prioritized in any diet plan and maintained long-term, regardless of whether you’re actively trying to lose weight. While a calorie deficit doesn’t need to be permanent, these healthy lifestyle changes should be. By focusing on these areas, you’ll not only support your weight goals but also improve your overall health for the long run.

Reference:
Sanaya, N., Janusaite, M., Dalamaga, M., & Magkos, F. (2024). The Physiological Effects of Weight-Cycling: A Review of Current Evidence. Current Obesity Reports, 13(1), 35–50. https://doi.org/10.1007/s13679-023-00539-8