Milk breaks a fast. It contains sugar in the form of lactose plus protein and fat, which provide calories and raise insulin, ending a fast even in small amounts.
| Calories | ~12-18 kcal per oz |
|---|---|
| Breaks a weight-loss fast? | Yes |
| Breaks ketosis? | Yes |
| Breaks autophagy? | Yes |
| Insulin impact | Yes |
Milk is a genuine food. It contains lactose, a sugar, along with protein and fat, so even a small pour delivers calories and a clear insulin response. A splash in coffee adds up faster than people expect, and a full glass certainly breaks a fast and stops autophagy.
Whole, skim, and most plant milks all contain enough sugar, protein, or calories to break a fast, though unsweetened almond and other very low-calorie plant milks are gentler in a small splash. If you want something in your coffee while fasting, unsweetened almond milk in a small amount is the closest to fast-safe.
Even a splash of dairy milk breaks a strict fast; on a loose weight-loss fast the impact of a small splash is minor but real.
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