If your Sunday nights are dedicated to meal prepping for the week ahead, you’re part of a mighty group of health nuts.
The planning ahead of meals is a main tip of weight loss coaches, food bloggers, and nutritionists.
Indeed, meal prepping’s popularity has exploded on social media. On Instagram alone there are 5.5 million photos tagged #mealprep and 1.1 million tagged #foodprep.
While perfectly portioned-out food for seven days does make for the perfect #foodporn snapshot, meal preppers are onto an idea that — at least in concept — is good for your diet, according to research.
People who spend more time preparing meals are more likely to have healthier diets, according to a 2014 study published in the American Journal of Preventive Medicine.
They eat more fresh fruits and vegetables.
They also eat at fast food restaurants only half as often as people who only spend less than an hour each day prepping and cooking their meals.
In addition, they spend less money on food.
More recently, a 2017 study of 40,000 adults in France found that people who meal prepped at least a few days at a time were less likely to be overweight and stuck more closely to nutritional guidelines.
The survey also found that meal prepping led to more food variety over the week.
Portion control is one key way food prepping helps people maintain a healthy weight or lose a few pounds.
A review of several studies around the role of portion control in weight management showed that eating the appropriate amount of food is directly linked.
One component of portion control that researchers stress is choosing the right portions of water-rich foods, like fruits and vegetables, and eating less energy-dense foods — like most fast foods and candy.
If you prep your food, it’s easier to not only eat the right amount, but to avoid foods that are bad for you but oh-so-tempting.
Food containers contain hazards
However, if you’re portioning food out into plastic containers, all of that healthy preparation could actually create a new barrier to staying trim.
Dr. Aly Cohen, a rheumatologist, as well as an integrative medicine and environmental health specialist who is on staff at the CentraState Medical Center, explained.
“An effective diet is not just about healthy eating, managing sugar and carbohydrates, and exercise,” she told Healthline. “Reducing chemical exposure is also key because many of these chemicals can disrupt normal hormone function, impede weight loss, and even cause weight gain. Just because chemicals may not have an obvious effect, like causing a rash, doesn't mean they aren’t tinkering with your body.”
Whipping up a big batch of healthy chili, scooping it out into several plastic containers, and quickly reheating it in the microwave come mealtime is one example of how a healthy meal prep turns into several dinners brimming with the harmful hormone-disrupting chemical bisphenol A (BPA).
BPA is found in polycarbonate plastic (plastic #7) and canned food linings, as well as many other things that we touch every day — including our smartphones.
“Most human exposure to BPA is through ingestion from canned products, but BPA can also be absorbed by touching paper that uses BPA to seal ink onto its surface [e.g., receipts, airplane and parking tickets, currency] and then touching your hands to your lips. BPA can also be absorbed in smaller amounts through the skin,” Cohen said.
Cohen noted that BPA is pervasive — 8 billion pounds of BPA are made every year — since it’s one of the cheapest ways to make packaging.
BPA and — if your plastic container is marked “BPA-free” — similar, sometimes more harmful chemicals are lurking in your plastic food storage set of containers.
Heating up plastic containers by putting hot food in them or microwaving them can draw out BPA — right into your food.
How BPA affects the body
BPA was first discovered in 1891 and then rediscovered in 1936, according to Cohen.
“It was used as an estrogen replacement drug for women, and it was also used to fatten poultry and cattle. In the 1940s it was discovered that linking the molecules together created a hard, clear, glass-like plastic,” she said.
BPA can confuse the endocrine system, which regulates hormones, by mimicking estrogen.
We’re regularly ingesting BPA, and therefore continually disrupting the messages that help our bodies function properly. In fact, according to the Centers for Disease Control and Prevention (CDC), more than 90 percent of people have detectable levels of BPA in their systems.
To date, nearly 100 studies have been published tying BPA to various health problems, from diabetes and cardiovascular disease to infertility, according to the Endocrine Society and IPEN's Introduction to Endocrine-Disrupting Chemicals.
Some other effects of too much BPA exposure are directly contrary to weight loss and healthy eating goals.
BPA may be wrecking your diet
BPA passes through a person’s system fairly quickly, but detoxifying still isn’t easy.
“Despite the fact that BPA has a short half-life of six hours, which means an exposure will wash out over a day or so, people continue to have high blood levels,” Cohen noted.
“There are two problems with BPA,” added Laura Vandenberg, PhD, a spokesperson for the Endocrine Society, and an assistant professor of environmental health at the University of Massachusetts Amherst. “One is that we are constantly exposed in our environment, so the levels never really seem to drop. Even in people that have been fasting, metabolite levels in urine are still detected. The second problem is that, if exposures occur during a vulnerable period of development, like fetal development, the effects can be permanent — even if exposures cease.”
For adult meal-planning fanatics, constant re-exposure to BPA may mean that meal prepping is actually sabotaging your diet.
“BPA is so ubiquitous, that humans are continuously exposed, making BPA ‘pseudo-persistent,’” Cohen said. “What’s interesting in terms of weight is that BPA can turn stem cells into fat cells and make fat cells turn larger. That’s not great news for our waistlines — let alone our overall health.”
A study published in Environmental Health Perspectives in 2015 was the first study to prove that BPA-glucuronide (BPA-G), which accounts for 80 to 90 percent of the metabolites your liver produces when processing BPA, doesn’t just get excreted from your body.
The researchers showed that BPA is an active agent that can prompt cells to become fat cells.
That’s not the only proven way that BPA exposure can interfere with your weight goals.
A recent study published in Endocrinology found that BPA exposure makes it much harder for you to feel full.
While meal prepping helps with portion control, the BPA in the plastic food storage containers may ironically be causing people to want to eat larger portions.
“BPA-free” label doesn’t equal safe
Even buying plastic containers marked “BPA-free” doesn’t protect you from the harmful effects of plastic.
Some BPA-free products can actually release estrogen-simulating chemicals that are more potent than BPA.
“Many products are now labeled ‘BPA-free.’ However, BPA is often replaced with bisphenol S [BPS] and bisphenol F [BPF], which are less studied but appear to have similar hormone-disrupting effects,” Rebecca Fuoco, MPH, director of Health Research Communication Strategies, told Healthline.
That means scientists and activists that study toxic chemicals like BPA and push to remove them from everyday products often end up spending a lot of time trying to figure out what’s in the new compound.
“When a chemical is found to be harmful, manufacturers change the molecule ever so slightly and put it out to market again,” noted Cohen. “From BPA came BPS, BPF, and BP-FB, which are molecules that have been found thus far to have more harmful effects than the chemical they were designed to replace — also known as ‘regrettable substitutions.’ Researchers are essentially playing whack-a-mole, because plastics and their ingredients are proprietary and considered ‘trade secrets,’ so the recipes and ingredients are not shared with researchers or consumers.”
Policy favors manufacturers
And reports of the harmful effects aren’t slowing production. The demand for BPA has risen 6 to 10 percent annually.
Oleoresin is a vegetable-based alternative that can add about two cents to the cost of manufacturing of cans, according to Cohen.
So far, it has only been used in a small percentage of cans on the market.
“Our government has given more priority to manufacturers than to consumers. The vast majority of food packing ingredients are going out to market without ever being tested for toxicity,” Cohen said.
In addition, the Food and Drug Administration (FDA) still considers BPA to be safe, stating on its website that their research has “showed that BPA is rapidly metabolized and eliminated through feces and urine.”
On the other hand, regulatory agencies in Europe have recently re-evaluated BPA. Last week, there was widespread agreement by countries in the European Union that this chemical should be labeled a human endocrine disruptor.
For Americans, though, toxic chemicals like BPA remain a concern.
“We shouldn't expect individual consumers to have detailed knowledge of chemistry to make safe decisions for themselves or their families. Safety decisions should be made by regulators using the best available evidence. I will continue to push for improved regulations that use modern data to protect public health,” Vandenberg told Healthline.
Four ways to avoid harmful diet-sabotaging chemicals
Even though BPA-riddled plastic containers are out there, Vandenberg and Cohen noted that people can still make small changes over time that add up.
Here are some ways to ensure your food containers aren’t keeping you from losing weight.
- Buy glass, ceramic, or stainless steel food containers. While cost can be a concern, avoid plastic containers whenever possible and invest in glass, ceramic, or stainless steel food storage containers instead. Remember that you shouldn’t assume that a “BPA-free” label means a plastic container is safe.
- Don’t heat up plastic containers or use harsh detergents to clean them. If you can’t shell out the cash for new glass food containers, there are still ways to make using your plastic containers safer. Using harsh cleaning supplies to wash your plastics or heating them up can increase leaching of BPA into food. Use eco-friendly soaps, never microwave plastics, and don’t pour hot liquids into your containers.
- Toss out worn or cracked BPA containers. Another way to make plastic containers safer is by tossing out the ones that are broken down or cracked. Clear hard plastic can often turn opaque from washing, and is more prone to breaking down in your food. Throw those containers into the trash and just use your newest, intact plastic containers.
- Buy fresh produce. “If you can, switch from canned food to flash-frozen organic — or even non-organic — food. Aim to buy fresh food whenever possible,” Cohen recommended. “Buying fresh foods instead of canned is also good, if possible. But eating healthy is also important, and if canned vegetables are the only affordable choice, they are better than no vegetables at all.” Vanderberg said.
Meal-prepping in plastic is still better than no meal prepping at all, if it helps you eat healthier.
“These chemicals are ubiquitous — they’re everywhere. You should do the best you can. Cutting chemicals out of your life is a journey, not a race. Every day I learn something new and try to add it into my life,” Cohen said.