24-Hour Fast: How It Affects Your Cholesterol, Blood Sugar and Metabolism

A 24-hour fast triggers significant changes in how your body uses energy and manages key health markers — including cholesterol levels, blood glucose and metabolic processes — as it switches from using food energy to stored fuels.

What a 24-Hour Fast Does to Cholesterol

• Short-term fasting may cause a temporary rise in total cholesterol, including both “bad” LDL and “good” HDL cholesterol, because fat stores are mobilised for energy during the fast.
• Some research suggests that repeated or structured fasting over weeks or months can improve overall lipid profiles, possibly lowering LDL and triglycerides in the long term.
• Cholesterol spikes seen during fasting generally return to baseline after normal eating resumes in healthy individuals, and long-term benefits depend on diet and lifestyle overall.

Effect on Blood Sugar Levels

• In the first hours of a fast, blood glucose levels usually fall as your body uses glycogen stored in the liver for energy.
• Once glycogen stores deplete (usually within 10–14 hours), the body begins burning fat and ketones become a key energy source, helping maintain glucose levels at a lower, more stable range.
• Lower insulin levels during fasting can improve insulin sensitivity and help stabilise glucose control in some people, although effects vary among individuals and depend on health status.

Metabolic Shifts During the Fast

• After about 12–14 hours without food, the body switches from using glucose to fat oxidation and ketone production for energy.
• Short-term fasting lowers overall energy expenditure and prompts hormonal changes — such as increased human growth hormone (HGH) — which help preserve muscle and enhance fat burning.
• These metabolic changes can support weight loss and improved fat utilisation when fasting is practised regularly as part of a broader eating strategy.

Important Considerations

• The effects of a single 24-hour fast differ markedly from long-term dietary patterns or repeated fasting routines; short-term changes don’t necessarily reflect sustained health outcomes.
• Fasting may not be safe for everyone — especially people with diabetes, thyroid issues, eating disorders, or other medical conditions — and should be done with medical guidance when needed.

As with any dietary approach, the impact of a 24-hour fast varies from person to person. While short-term fasting can trigger useful metabolic changes, experts advise that it should be practised thoughtfully and, in some cases, under medical guidance to ensure it supports overall health rather than causing unintended risks.

Disclaimer : This article is for informational purposes only and should not be considered medical advice. Readers are advised to consult a qualified healthcare professional before making any changes to their diet or lifestyle.