I frequently hear patients say some version of, “whenever I start to eat less (or start a diet), I look worse.” This is an extremely common scenario which causes people to abandon their diet in the early stages. Usually, when they go back to eating the same amount as before, they tend to look a little better, which reinforces their aversion to dieting.
I completely understand the frustration because right when the diet is in the most difficult early stages, your body often looks worse than ever. There are three major reasons that explain this clearly.
Muscles flatten. To simplify it, glycogen (stored carbohydrates) and water exist in muscle and notably inflate them. When on a diet, the decreased carbohydrate intake leads you to use up the glycogen for energy. Since each gram of glycogen is stored with roughly 3 grams of water, the muscles flatten as you use the glycogen and lose the water in them. To summarize, your body fat stays the same while muscles lose volume which can describe the “skinny fat,” feeling at the beginning of a diet.
Increased cortisol (mainly with large deficits). Fasting and very aggressive calorie cuts can raise cortisol, which breaks down your glycogen stores to increase your blood sugar. Since it’s the year 2026 and food is basically everywhere around us, this no longer serves us for survival, but it can have an effect on your appearance. Cortisol can promote water retention in the extracellular space (outside the cell), which can make you look “softer” than normal. Notably, a meta-analysis found that fasting raised cortisol while more moderate calorie restriction did not, which is one more reason to keep your deficit moderate.
It takes time for the body to start using fat. To put it simply, when a calorie restriction starts, the body has mechanisms to use up carbohydrates and protein relatively quickly. It takes time for the body to get the system running to burn fat (aka fat oxidation). Combine this with point one above and you find that the scale is usually dropping but it’s basically all water weight- your body fat is staying the same while your muscles are flattening usually causing this dramatically worsened appearance.
The solution to this is simple although understandably difficult.
Commit to the process, and stick it out despite whatever changes in appearance you’re noticing. It’s easier to maintain than it is to achieve a certain look which can be comforting.
Keep the calorie deficit low to moderate, keep protein appropriately high, and incorporate resistance training.
Keep in mind that day to day our appearance is very fickle. Sleep (poor sleep can raise cortisol), bowel contents, hydration, salty meals, etc can all also change your appearance which can easily mask any progress you’re making.
Save calories for night time, especially carbohydrates, if you’re sleeping poorly on a calorie restriction
There are multiple tools and tricks not mentioned here to get through the early phases of body recomposition. Book a free 30-minute call to discuss in more detail.
References:
Point 1: Muscles flatten (glycogen + bound water)
Müller MJ, Bosy-Westphal A. Effect of over- and underfeeding on body composition and related metabolic functions in humans. Curr Diab Rep. 2019.
Bosy-Westphal A, Enderle J, Norman K, Müller MJ. Defining healthy weight loss and target weight in the era of highly effective treatment of patients with obesity. J Cachexia Sarcopenia Muscle.2026.
Point 2: Increased cortisol
Nakamura Y, Walker BR, Ikuta T. Systematic review and meta-analysis reveals acutely elevated plasma cortisol following fasting but not less severe calorie restriction. Stress. 2015.
Braun TP, Marks DL. The regulation of muscle mass by endogenous glucocorticoids. Front Physiol.2015.
Swarbrick M, Zhou H, Seibel M. Mechanisms in endocrinology: local and systemic effects of glucocorticoids on metabolism: new lessons from animal models. Eur J Endocrinol. 2021.
El-Farhan N, Rees DA, Evans C. Measuring cortisol in serum, urine and saliva – are our assays good enough? Ann Clin Biochem. 2017.
Castle-Kirszbaum M, Goldschlager T, Shi MDY, Fuller PJ. Glucocorticoids and water balance: implications for hyponatremia management and pituitary surgery. Neuroendocrinology. 2023.
Point 3: Fat oxidation lags
Müller MJ, Bosy-Westphal A. Effect of over- and underfeeding on body composition and related metabolic functions in humans. Curr Diab Rep. 2019.
Bosy-Westphal A, Enderle J, Norman K, Müller MJ. Defining healthy weight loss and target weight in the era of highly effective treatment of patients with obesity. J Cachexia Sarcopenia Muscle.2026.
Written by Mahiar Rabie, MD, MS. No AI was used in the writing of this article, only for collection of references and a later fact-check edit (glycogen water ratio and cortisol section). Of note, there are numerous mechanisms that cause this issue while in a calorie deficit. This article is a simplified summary. This is not meant to serve as medical advice. Contact your physician for medical advice if it’s needed.
