by Chad Kerksick PhD July 05, 2011 3 min read
A neat study was published in the prestigious New England Journal of Medicine in June 2011 by researchers who are part of the Harvard School of Public Health. If you keep track of health and medicine, Harvard University glows with excellence compared to many other places. This study analyzed the food and activity habits of 120,877 U.S. men and women . Before you ask, “no that’s not a typo.” This is an impressive number of research subjects and a host of diet and exercise factors were analyzed over 4-year periods from several groups of data.
For starters, over an average 4-year period, participants gained an average of 3.35 pounds or 0.84 pounds per year. Not good news for sure and another example of the ongoing trouble the American public has with controlling their body weight. The authors then compared these changes in body weight with several different types of food which are commonly ingested. What types of foods exactly, you ask? Foods like potato chips, potatoes, sugar-sweetened beverages, unprocessed and processed meats, whole grains, nuts, fruits and yogurt were the dirty culprits they put under fire. As many of you may guess, their results were somewhat predictable, but this shouldn’t take away from the importance of their results. Consumption of potatoes, sugar-laden beverages and processed and unprocessed meats were all associated with a greater increase in body mass while consumption of nuts, fruits, whole grains and yogurt were all related to a decrease in body mass over every four-year period.
In fact and what is most interesting about how their findings were presented, the authors came up with an estimate of how much the consumption of each food impacted changes in body mass. For example, consuming potato chips was estimated to be responsible for 1.69 of the average 3.35 pounds that were gained every four years. Potatoes (baked, mashed, etc.) were responsible for 1.28 pounds and sugar-sweetened beverages were linked to 1.00 pounds. Finally, unprocessed (0.95 pounds) and processed meats (0.93 pounds) were found to be significantly related to the overall weight gain seen from the 120+ thousand people.
Now, for some good news! Regular vegetable intake was suggested to decrease body weight by 0.22 pounds, with similar reductions being found for whole grains (0.37 pounds), fruits (0.49 pounds) and nuts (0.57 pounds). Impressively, yogurt ingestion was found to be responsible for 0.82 pounds of weight loss every four years.
Now before people start saying “this food is bad” and “that food is good”, some perspective needs to be drawn. For starters, a number of sources of error can exist for these types of studies, but I strongly believe that their findings are reflective of the general impact certain foods may have on weight gain. As you can imagine, potato farmers in Idaho are livid with these results while nuts farmers are licking their chops. In fact, I read a press release that a national governing board for pistachios was already developing a marketing campaign centered upon these study results.
My interpretations are simple, certain foods can make it more challenging to lose weight as well as maintain any progress you may make in your daily diet. Based off of the results of this study, being aware of how many French fries you eat or containers are regular sugar soft drinks or sweetened tea is important and may be responsible for anywhere from 30 – 50% of the weight you gain. Additionally, increasing consumption of nuts, fruits, vegetables, whole grains, etc. or replacing your intake of other foods with these types of foods is certainly a positive habit that will help with weight loss and more so weight maintenance. Again, these are all things many people probably already knew, but seeing a number that says anywhere from 30 to 50% of the weight gained over a four-year period could be due largely your intake of certain foods makes an impact and may make you think twice about upsizing your fast food order, getting apples instead or only eating half of what they give you.
While I firmly believe there is no single “bad food” out there, only those consumed repeatedly in too high of quantities, these findings do allow people to understand more the impact (both positive and negative) of ingesting certain foods. Particularly, I feel, these results are more meaningful for people trying to maintain some weight loss or establish a healthy life as they are intended to reflect the impact of changes in weight over a four-year period versus changes in a few weeks or months of dieting.