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  • Writer's pictureKyle Becker

The Surprising Truth: How Eating Too Little Can Make You Gain Fat

Uncovering the 6 ways undereating can hinder your weight loss goals and harm your health

Are you struggling to lose weight despite cutting your calorie intake drastically? The truth is, undereating could actually be sabotaging your weight loss efforts. In this blog post, we'll explore the science behind this counterintuitive phenomenon and discuss six ways that eating too little can make you gain fat, backed by research.

1. Loss of muscle and difficulty building muscle

When you consume fewer calories than your body needs, it enters a catabolic state, breaking down muscle tissue to meet energy demands. Research by Pasiakos et al. (2010) has shown that a low-calorie diet can decrease muscle protein synthesis and increase muscle protein breakdown[1]. Consequently, losing muscle mass can make it harder to achieve a toned physique and may also lower your resting metabolic rate, further hindering your weight loss progress.

2. Slower metabolism

Did you know that undereating can slow down your metabolism? A study conducted during World War II, known as the Minnesota Starvation Experiment, showed that prolonged low-calorie intake led to a significant reduction in resting metabolic rate (RMR) in participants[2]. This decrease in RMR persisted even after the participants started eating more calories again, making it more difficult to lose weight and maintain weight loss.

3. Less energy for movement and exercise

If you're feeling sluggish and lacking the energy to exercise, undereating might be to blame. A study by Redman et al. (2014) found that participants on a calorie-restricted diet had reduced spontaneous physical activity and experienced increased fatigue[3]. With less energy for exercise and daily activities, it becomes harder to maintain an active lifestyle, which is essential for weight loss and overall health.

4. Hormonal shift towards fat storage

Eating too little can cause hormonal changes that promote fat storage. For example, ghrelin, the "hunger hormone," increases when you're not consuming enough calories, while leptin, the "satiety hormone," decreases[4]. This hormonal shift can encourage fat storage and make it difficult to lose weight, even if you're eating fewer calories.

5. Binging tendencies

When you're not eating enough, your body may respond by craving high-calorie foods, which can lead to overeating. A review by Polivy and Herman (2007) found that dietary restraint and calorie restriction can trigger binge eating episodes in individuals[5]. Developing healthy eating habits and maintaining a balanced diet can help manage your appetite and prevent binge eating.

6.Nutrient deficiencies

Undereating can make it challenging to get enough of the essential vitamins and minerals necessary for optimal health. A review by Paddon-Jones et al. (2011) concluded that inadequate protein intake, which can result from undereating, is associated with various health problems, including muscle wasting, impaired immunity, and poor wound healing[6]. Ensuring you consume enough calories and a balanced diet is crucial for getting the nutrients your body needs.


In conclusion, achieving sustainable weight loss requires a balanced approach to diet and exercise, rather than resorting to extreme calorie restriction. As the studies mentioned throughout this blog post have shown, undereating can lead to muscle loss (Pasiakos et al., 2010), a slower metabolism (Minnesota Starvation Experiment), decreased energy for exercise (Redman et al., 2014), hormonal shifts that promote fat storage, binging tendencies (Polivy and Herman, 2007), and nutrient deficiencies (Paddon-Jones et al., 2011). By understanding these potential consequences, you can make informed decisions about your diet and exercise routine to reach your weight loss goals in a healthy and sustainable manner.

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