Quick answers
Does bone broth break a fast?
It has protein and calories, so yes. But it has a place, especially at the end of a longer fast
Why a little broth counts
A fast isn't only about calories. While you fast, insulin falls and your fat tissue releases fatty acids for your muscles and liver to burn. Anything that pushes insulin back up slows that release. Protein does this more than most people expect: in a study of 38 everyday foods, protein foods such as meat and fish released much more insulin than their effect on blood sugar would suggest 1.
If you want broth for the salt
People often reach for broth on long fasts because they feel flat or get a headache. That's often salt and water. Insulin tells your kidneys to hold on to sodium, so when it falls during a fast you lose more salt and water 3,2.
- Fasts of 12 to 16 hours: water when you're thirsty is usually enough.
- Fasts of 18 to 24 hours: if you get a headache or feel lightheaded when you stand up, try a pinch of salt in water.
- Fasts longer than a day: plan them with a doctor, especially if you take any medication.
Where broth fits: breaking a longer fast
Broth is a good first meal after a fast of a day or more: Fasting Tracker's guide suggests breaking it with a small, easy meal such as soup, eggs or yoghurt, and returning to normal meals over the next day. After several days with little or no food, restarting eating needs medical care because of refeeding syndrome 5.
Sources
- Holt SH, Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997;66(5):1264-76. doi.org/10.1093/ajcn/66.5.1264
- Sigler MH. The mechanism of the natriuresis of fasting. J Clin Invest. 1975;55(2):377-87. doi.org/10.1172/JCI107941
- DeFronzo RA, Cooke CR, Andres R, et al. The effect of insulin on renal handling of sodium, potassium, calcium, and phosphate in man. J Clin Invest. 1975;55(4):845-55. doi.org/10.1172/JCI107996
- He FJ, Li J, Macgregor GA. Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials. BMJ. 2013;346:f1325. doi.org/10.1136/bmj.f1325
- Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. BMJ. 2008;336(7659):1495-8. doi.org/10.1136/bmj.a301
Keep reading
Water, salt and electrolytesWhy fasting changes how your body handles water and sodium, and when it's worth doing something about it- The 24-hour fastDinner to dinner: a full day of fasting, for experienced fasters, once in a while
How to break your fast wellYour first meal shapes the rest of your day. Here's what the research says about getting it right
A note on health
Fasting Tracker is designed for general wellness and is not a medical device. Fasting is not right for everyone. If you are pregnant, diabetic, have a history of eating disorders or take medication, talk to your doctor first, and before any extended fast.