The recommended amount of soy consumption per day is a controversial issue. Different studies and organizations recommend different amounts. Should we avoid soy altogether? Or perhaps a little bit of soy is good for you? Or can we consume as much as we would like? How much soy is too much?
To find the answers watch this 2-minute video from NutritionFacts.org:
What is one serving of soy? 
Soy yogurt – 1 cup
Tofu – 3 ounces
Soymilk – 1 cup
Edamame – 1/2 cup
Soy “burger” – 1 patty
Tempeh – 3 ounces
Soy pasta – 1/2 cup (cooked)
Soy nutrition bar – 1 bar
Soy nuts, roasted – 1/4 cup
Soy breakfast patty – 2 patties
Meatless soy crumbles – 1/3 cup
Soy chips – 1 bag
Soy nut butter – 2 Tbsp
 Nagata C, Shimizu H, Takami R, Hayashi M, Takeda N, Yasuda K. Dietary soy and fats in relation to serum insulin-like growth factor-1 and insulin-like growth factor-binding protein-3 levels in premenopausal Japanese women. Nutr Cancer. 2003;45(2):185-9.
 Dewell A, Weidner G, Sumner MD, Barnard RJ, Marlin RO, Daubenmier JJ, Chi C, Carroll PR, Ornish D. Relationship of dietary protein and soy isoflavones to serum IGF-1 and IGF binding proteins in the Prostate Cancer Lifestyle Trial. Nutr Cancer. 2007;58(1):35-42.
 Arjmandi BH, Khalil DA, Smith BJ, Lucas EA, Juma S, Payton ME, Wild RA. Soy protein has a greater effect on bone in postmenopausal women not on hormone replacement therapy, as evidenced by reducing bone resorption and urinary calcium excretion. J Clin Endocrinol Metab. 2003 Mar;88(3):1048-54.