OET interlinear PSA 109:24

uW Translation Notes:

Note 1 topic: figures-of-speech / metonymy

בִּ֭רְכַּ⁠י כָּשְׁל֣וּ

(Some words not found in UHB: knees_of,my weak from,fasting and,flesh_of,my become_gaunt from,fatness )

Here, knees represents the strength of the whole body. If it would be helpful in your language, you could use an equivalent expression or plain language. Alternate translation: [My body is weak]

Note 2 topic: grammar-connect-logic-result

מִ⁠צּ֑וֹם

from,fasting

The word from indicates that fasting is the reason for the weakness described in the first part of the verse. Use a connector in your language that makes it clear that the fasting is the cause of the weakness. Alternate translation: [because of fasting very much]

Note 3 topic: figures-of-speech / explicit

וּ֝⁠בְשָׂרִ֗⁠י כָּחַ֥שׁ מִ⁠שָּֽׁמֶן

(Some words not found in UHB: knees_of,my weak from,fasting and,flesh_of,my become_gaunt from,fatness )

By my flesh is gaunt from fatness, David means that his flesh is gaunt from the complete absence of fat. You could indicate this explicitly in your translation if that would be helpful to your readers. Alternate translation: [and my flesh is gaunt, very far from being fat]