<PAGE>   1
 
                                                                    EXHIBIT 11.1
 
                        GENERAL NUTRITION COMPANIES, INC
                                AND SUBSIDIARIES
                     COMPUTATION OF NET EARNINGS PER SHARE
 
<TABLE>
<CAPTION>
                                                                   YEAR           YEAR           YEAR
                                                                   ENDED          ENDED          ENDED
                                                                FEBRUARY 4,    FEBRUARY 3,    FEBRUARY 1,
           (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)                 1995           1996           1997
-------------------------------------------------------------   -----------    -----------    -----------
<S>                                                             <C>            <C>            <C>
Net earnings before extraordinary items......................     $45,744        $69,146        $ 3,935
Loss from extraordinary items................................      (8,550)            --             --
                                                                -----------    -----------    -----------
Net earnings available for common shares.....................     $37,194        $69,146        $ 3,935
                                                                 ========       ========       ========
Elimination of tax effected interest expense on convertible
  debt for fully diluted per share calculations..............     $ 1,759        $   872        $    --
                                                                 ========       ========       ========
Common stock.................................................      76,378         82,406         84,907
Outstanding warrants.........................................       1,340             --             --
Outstanding options..........................................       2,310          3,454          1,387
                                                                -----------    -----------    -----------
Primary weighted average common shares.......................      80,028         85,860         86,294
                                                                 ========       ========       ========
Common stock.................................................      76,378         82,406         84,907
Outstanding warrants.........................................       1,356             --             --
Outstanding options..........................................       2,364          3,875          1,501
Conversion of convertible debt into common stock.............       8,196          3,976             --
                                                                -----------    -----------    -----------
Fully diluted weighted average common shares.................      88,294         90,257         86,408
                                                                 ========       ========       ========
PRIMARY EARNINGS PER SHARE:
  Earnings before extraordinary items........................     $  0.57        $  0.81        $  0.05
  Loss from extraordinary items..............................       (0.11)            --             --
                                                                -----------    -----------    -----------
  Total earnings per share...................................     $  0.46        $  0.81        $  0.05
                                                                 ========       ========       ========
FULLY DILUTED EARNINGS PER SHARE:
  Earnings before extraordinary items........................     $  0.54        $  0.78        $  0.05
  Loss from extraordinary items..............................       (0.10)            --             --
                                                                -----------    -----------    -----------
  Total earnings per share...................................     $  0.44        $  0.78        $  0.05
                                                                 ========       ========       ========
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