“Starvation mode” describes the body’s adaptive response to prolonged calorie restriction. When the body detects it’s not getting enough calories, it conserves energy by slowing metabolism. This can hinder the weight loss progress and may even lead to weight gain. (1)

Ph.D. in Sports Physiology Dr. Mike Israetel took to YouTube on July 23, 2024, to demystify the starvation mode theory, offering a scientific breakdown of the body’s response to extended calorie restriction. Check it out below:

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When Starvation Mode Is Not a Myth

Gaining muscle tissue on a hypocaloric diet is nearly impossible. “If you cut your calories low enough for long enough, you will lose weight,” Israetel explained. 

However, Israetel cautions that significant caloric deficits can put considerable demands on the body, often leading to predictable symptoms. Ignoring these signs can exacerbate them, jeopardizing the ability to maintain muscle mass while losing fat. 

6 Signs of Diet Fatigue

Israetel explains that starvation mode is commonly misunderstood. People who are genuinely starving will undeniably lose weight. However, a state known as ‘diet fatigue’ can arise from extreme calorie restriction.

Starvation mode is very high diet fatigue.

 Diet fatigue manifests in six main ways:

Rabid hunger and cravings

Incredibly lower energy for training and movement

Lowered ability to think clearly, quickly, and deeply

Consistently reduced sleep quality

Feeling cold all the time

Increased water retention

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1. Rabid hunger and cravings

When an individual restricts their calorie intake excessively or sustains it for an extended period, their body triggers intense hunger signals. This can make it difficult to stick to a diet and may lead to overeating or binge eating.

It’s a sign…it is less than productive to continue that mode.

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2. Lower energy for training and movement

Diet fatigue can make workouts and daily activities feel like an uphill battle. This can be frustrating and demotivating, hindering the ability to maintain a consistent exercise routine. “Several contest preps ago, I got to a point where walking was physically difficult,” said Israetel. (2)

3. Lowered ability to think clearly, quickly, and deeply

Prolonged diet fatigue can cause cognitive difficulties, including problems concentrating, remembering information, or making decisions, negatively affecting work, studies, and overall well-being. This is a telltale sign of diet fatigue if you consistently starve before your next meal. 

4. Consistently reduced sleep quality

Starvation mode can significantly disrupt sleep patterns, making it difficult to fall asleep, stay asleep, or wake up feeling refreshed. Poor sleep can exacerbate other diet fatigue symptoms and impede weight loss.

Image via Shutterstock/Gatot Adri

Sound sleep is crucial for fat loss and muscle growth. Poor sleep, in terms of quality and duration, makes muscle retention and fat loss difficult, explains Israetel. (3)

5. Feeling cold all the time

During diet fatigue, the body may conserve energy by lowering its core temperature, causing you to feel chilly even in relatively warm environments. It is usually a result of decreased thyroid hormone production, which can negatively impact your future fat-burning potential.

6. Increased water retention

Starvation mode can cause your body to retain more water as a side effect of increased fat burning. This can lead to bloating and mask fat loss progress, making it seem like you’re not making any progress, even if you are.

Should You Avoid Diet Starvation?

Israetel clarifies that while “starvation mode” may not be the most accurate term, extreme diet fatigue can indeed occur, leading to suboptimal fat loss results.

It may indicate an overly restrictive diet to experience several of these six signs for multiple weeks consistently. Israetel recommends transitioning to a maintenance phase or a slight calorie surplus to reset your metabolism and alleviate diet fatigue before resuming your fat-loss efforts.

References 

Johannsen DL, Knuth ND, Huizenga R, Rood JC, Ravussin E, Hall KD. Metabolic slowing with massive weight loss despite preservation of fat-free mass. J Clin Endocrinol Metab. 2012 Jul;97(7):2489-96. doi: 10.1210/jc.2012-1444. Epub 2012 Apr 24. Erratum in: J Clin Endocrinol Metab. 2016 May;101(5):2266. doi: 10.1210/jc.2016-1651. PMID: 22535969; PMCID: PMC3387402.

Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes (Lond). 2010 Oct;34 Suppl 1(0 1):S47-55. doi: 10.1038/ijo.2010.184. PMID: 20935667; PMCID: PMC3673773.

Chaston TB, Dixon JB, O’Brien PE. Changes in fat-free mass during significant weight loss: a systematic review. Int J Obes (Lond). 2007 May;31(5):743-50. doi: 10.1038/sj.ijo.0803483. Epub 2006 Oct 31. PMID: 17075583.

Featured image via Shutterstock/Gatot Adri

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