The business, which includes Carluke based jam maker R&W Scott, among its subsidiaries, expects earnings before interest, tax, depreciation and amortisation to be £3.3 million in the 12 months to March 31.
That would compare to EBITDA of £10.5m which resulted in an underlying pre-tax profit of £6.3m in the previous year.
The Napier Brown subsidiary is involved in a pricing dispute with British Sugar, owned by Associated British Food, and has made a complaint which has been referred to the Competition and Markets Authority.
Real Good Food said its Garret Ingredients arm was also feeling the impact of that but admitted: "The group remains unable to be definite on a timetable for the resolution of the dispute."
It said that problems had masked good progress in other parts of the company which included year-on-year EBITDA growth at bakery ingredients firm Renshaw and dessert maker Haydens.
Other group businesses were said to be in "good shape" with investment in R&W Scott delivering sales growth.
Shares closed up 0.5p at 38.5p.