In both French and English, there are two units called calorie, with a lowercase C except as required at the start of a sentence. Which one is meant depends on the context.
- In a physics or chemistry context, a calorie (Fr.: calorie) is an amount of energy equal to 4.184 J, or (if indicated by the context) the amount of energy required to warm one gram of water by 1 degree Kelvin in certain temperature and pressure conditions. This meaning is sometimes disambiguated by specifying small calorie (Fr.: petite calorie).
- In a physiology or nutrition context, a calorie (Fr.: calorie) is an amount of energy equal to a kilocalorie (Fr.: kilocalorie), i.e. 1000 small calories. The SI prefix in the word kilocalorie forces the physics interpretation of the calorie stem. This meaning is sometimes disambiguated by specifying large calorie (Fr.: grande calorie). Occasionally, in both French and English, the word is spelled with a capital C, but this is not very common.
The Québecois Grand Dictionnaire terminologique lists both meanings under different subject headings, like the French Trésor de la langue française.
Physical units, unlike French or English words, are case-sensitive; 1 cal is one small calorie and 1 Cal is one large calorie.
So from a linguistic point of view, “150 calories” (Fr.: “150 calories”) is correct to mean 150 kcal. It is not a bogus claim, but it can be viewed as purposefully unclear.