It depends on the overall diet and what food or drink it is replacing. For example, if you are already following a diet that is high in calories, adding tomato juice to your diet may not help you lose weight. On the other hand, if you replace a sugar-sweetened beverage like soda with tomato juice, you may see some weight loss. This is because tomato juice has a lower calorie and sugar content than soda. Furthermore, it contains nutrients that may help with weight loss, such as fiber.