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They block carbs from being digested, apparently allowing you to eat carbs without (some) of the unwanted calories. But are they really as beneficial as they sound?
This is a detailed review of carb blockers and their effects on your health and weight.
What are Carb Blockers?
Carb blockers, also known as starch blockers, can help block the enzymes needed to digest certain carbs.
Some types are sold as weight loss supplements. They're made from a group of compounds called alpha-amylase inhibitors, which occur naturally in certain foods.
In this article, the term carb blocker will refer to the nutritional supplement containing bean extract, not the prescription medications.
Bottom Line: The type of carb blocker discussed in this article is a dietary weight loss supplement extracted from beans.
How Do Carb Blockers Work?
Digestible carbs can be split into two main groups: simple and complex carbs.
Complex carbs are made up of many simple carbs linked together to form chains, which have to be broken down by enzymes before they can be absorbed.
Carb blockers contain substances that inhibit some of the enzymes that break down these complex carbs (3).
As a result, these carbs then pass into the large intestine without being broken down or absorbed. They do not contribute any calories or raise blood sugar.
Bottom Line: Carb blockers inhibit enzymes that digest complex carbs, preventing the carbs from providing calories or raising blood sugar.
Carb Blockers May Help with Weight Loss
Carb blockers are usually marketed as weight loss aids. They are advertised as allowing you to eat as many carbs as you desire without providing any calories.
However, their effectiveness may be limited and studies provide conflicting results.
How Effective are Carb Blockers?
Carb blockers only prevent a portion of the carbs you eat from being digested. At best, they appear to block 50–65 percent of carb-digesting enzymes (5).
It's important to note that inhibiting these enzymes does not necessarily mean the same proportion of carbs will be blocked.
One study examining a strong carb blocker found that even though it could inhibit 97 percent of the enzymes, it only prevented 7 percent of the carbs from being absorbed (6).
This may happen because carb blockers don't directly prevent carbs from being absorbed. They may simply increase the amount of time it takes for the enzymes to digest them.
On top of that, the complex carbs affected by carb blockers make up only part of the carbs in most people's diets.
For many people trying to lose weight, the added sugars in processed foods are a bigger problem. Added sugars are usually simple carbs like sucrose, glucose or fructose. These are not affected by carb blockers.
Bottom Line: Carb blockers only block a small percentage of carbs from being absorbed and their effectiveness depends on the type of carbs you eat.
What Does the Evidence Say?
Several studies show that carb blockers may be able to cause some weight loss.
The studies ranged from 4–12 weeks long and people taking carb blockers usually lost between 2–5.5 lbs (0.95–2.5 kg) more than the control groups. One study showed up to 8.8 lbs (4 kg) greater weight loss than the control group (7, 8, 9, 10).
Interestingly, the people who ate the most carbs appear to be the same ones who lost weight while using these supplements (11).
This makes sense because the higher the proportion of complex carbs in your diet, the bigger the difference carb blockers can make.
Unfortunately, most of these studies were small, poorly designed and largely funded by supplement companies, meaning the results may not be very reliable.
More independent, high-quality studies are needed.
Bottom Line: Some studies have shown that carb blockers can help you lose up to 2–9 lbs (0.95–4 kg) of weight, while others show no effect.
Carb Blockers May Decrease Appetite
One rat study found that the phytohaemagglutinin in carb blockers did cause a significant decrease in food intake. The rats that had been given the compound ate between 25–90 percent less. However, this effect lasted only a few days (2).
By the eighth day of the experiment, the effects wore off and the rats ate just as much as before. Additionally, once they stopped taking carb blockers, the rats ate up to 50 percent more than before to compensate and returned to their previous weights (2).
However, there may be other ways that carb blockers decrease appetite.
Similar studies found that a carb blocker supplement could decrease the amount of food the rats ate by 15–25 percent over a consistent period of time and even caused them to eat less of foods that are high in fat and sugar (2).
This effect has not been well-researched in humans, but one recent study found that a concentrated, standardized bean extract did decrease feelings of hunger, probably by suppressing levels of the hunger hormone ghrelin (6).
It's hard to say if this effect is achieved with the carb blocker supplements currently on the market or if the effect can actually contribute to weight loss in humans.
Bottom Line: Some animal and human studies suggest that carb blockers can decrease appetite and cravings, but more studies are needed.
Carb Blockers May Help Control Blood Sugar
Carb blockers are usually marketed as weight loss supplements, but they probably have a bigger impact on blood sugar control.
They prevent or slow down the digestion of complex carbs.
As a result, they also lower the spike in blood sugar levels that would normally happen when those carbs are absorbed into the blood stream.
However, this is only true for the percentage of carbs that are actually affected by the carb blockers.
In addition, carb blockers are thought to affect some of the hormones involved in controlling blood sugar levels (5).
In several studies of healthy people, carb blocker supplements have been shown to cause a smaller rise in blood sugar after consuming a meal high in carbs. They also cause blood sugar levels to return to normal faster (1, 5, 13).
Bottom Line: Studies have shown that carb blockers can cause blood sugar to rise less and return to normal faster after a meal.
Carb Blockers Provide Beneficial Resistant Starch
Carb blockers have another unintended benefit—they increase the amount of resistant starch in the large intestine.
This is because they decrease the amount of carbs that are absorbed in the small intestine, thereby increasing the starch that runs through the gut.
Similar to fiber, resistant starches are any starches in food that cannot be digested by the enzymes in the small intestine.
When resistant starches pass into the large intestine, gut bacteria ferment them and release gasses and beneficial short-chain fatty acids.
When carb blockers prevent the digestion of complex carbs in the small intestine, these carbs function like resistant starches.
Additionally, resistant starches may help increase the amount of fat your body burns after a meal (17).
Bottom Line: When carb blockers cause carbs to pass into the large intestine undigested, these carbs act as resistant starch. Resistant starch has been linked to many health benefits.
Are Carb Blockers Safe?
Carb blockers are generally considered safe, but make sure to buy them from a reputable source.
Safety and Side Effects
As far as side effects are concerned, carb blockers are considered very safe.
However, when carbs are fermented by bacteria in the large intestine, the gasses they release can result in a number of uncomfortable side effects.
These side effects are usually not severe and go away with time, but they are enough for some people to stop taking carb blockers.
Additionally, people with diabetes who take insulin should talk to a doctor before taking carb blockers, since there is a chance they could cause low blood sugar if the insulin dose is not adjusted.
Bottom Line: Carb blockers are usually safe, although they can cause uncomfortable side effects.
Another issue is supplement regulation.
Supplement manufacturers are themselves responsible for the safety and integrity of their products, and there have been many cases of fraud in the supplement industry.
In the past, the FDA has even found dietary supplements that were adulterated with prescription medications that had previously been removed from the market due to their dangerous side effects.
These potentially harmful medications had been added in an attempt to make the supplements more effective (19).
For this reason, chances are that many of the carb blockers you can buy in the store don't actually contain what is listed on the label.
When it comes to supplements, it's always a good idea to do some research and buy from a reputable manufacturer.
Bottom Line: Even though carb blockers are usually safe, it's hard to say if supplements will really contain what they say on the label.
Should You Take a Carb Blocker?
A few studies suggest carb blockers can help cause a small amount of weight loss, reduce appetite and lower blood sugar levels.
However, studies haven't been high enough in quality to show whether carb blockers have any real long-term effect. Plus, they are probably only helpful for people following a moderate-to-high-carb diet.
Regardless, carb blocker supplements are just that—supplements. They are no substitute for a healthy lifestyle.
This article was reposted from our media associate Authority Nutrition.
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By Tara Smith
Fires in the Brazilian Amazon have jumped 84 percent during President Jair Bolsonaro's first year in office and in July 2019 alone, an area of rainforest the size of Manhattan was lost every day. The Amazon fires may seem beyond human control, but they're not beyond human culpability.
Bolsonaro ran for president promising to "integrate the Amazon into the Brazilian economy". Once elected, he slashed the Brazilian environmental protection agency budget by 95 percent and relaxed safeguards for mining projects on indigenous lands. Farmers cited their support for Bolsonaro's approach as they set fires to clear rainforest for cattle grazing.
Bolsonaro's vandalism will be most painful for the indigenous people who call the Amazon home. But destruction of the world's largest rainforest may accelerate climate change and so cause further suffering worldwide. For that reason, Brazil's former environment minister, Marina Silva, called the Amazon fires a crime against humanity.
From a legal perspective, this might be a helpful way of prosecuting environmental destruction. Crimes against humanity are international crimes, like genocide and war crimes, which are considered to harm both the immediate victims and humanity as a whole. As such, all of humankind has an interest in their punishment and deterrence.
Crimes against humanity were first classified as an international crime during the Nuremberg trials that followed World War II. Two German Generals, Alfred Jodl and Lothar Rendulic, were charged with war crimes for implementing scorched earth policies in Finland and Norway. No one was charged with crimes against humanity for causing the unprecedented environmental damage that scarred the post-war landscapes though.
Our understanding of the Earth's ecology has matured since then, yet so has our capacity to pollute and destroy. It's now clear that the consequences of environmental destruction don't stop at national borders. All humanity is placed in jeopardy when burning rainforests flood the atmosphere with CO₂ and exacerbate climate change.
Holding someone like Bolsonaro to account for this by charging him with crimes against humanity would be a world first. If successful, it could set a precedent which might stimulate more aggressive legal action against environmental crimes. But do the Amazon fires fit the criteria?
Prosecuting crimes against humanity requires proof of widespread and systematic attacks against a civilian population. If a specific part of the global population is persecuted, this is an affront to the global conscience. In the same way, domestic crimes are an affront to the population of the state in which they occur.
When prosecuting prominent Nazis in Nuremberg, the US chief prosecutor, Robert Jackson, argued that crimes against humanity are committed by individuals, not abstract entities. Only by holding individuals accountable for their actions can widespread atrocities be deterred in future.
The International Criminal Court's Chief Prosecutor, Fatou Bensouda, has promised to apply the approach first developed in Nuremberg to prosecute individuals for international crimes that result in significant environmental damage. Her recommendations don't create new environmental crimes, such as "ecocide", which would punish severe environmental damage as a crime in itself. They do signal, however, a growing appreciation of the role that environmental damage plays in causing harm and suffering to people.
The International Criminal Court was asked in 2014 to open an investigation into allegations of land-grabbing by the Cambodian government. In Cambodia, large corporations and investment firms were being given prime agricultural land by the government, displacing up to 770,000 Cambodians from 4m hectares of land. Prosecuting these actions as crimes against humanity would be a positive first step towards holding individuals like Bolsonaro accountable.
But given the global consequences of the Amazon fires, could environmental destruction of this nature be legally considered a crime against all humanity? Defining it as such would be unprecedented. The same charge could apply to many politicians and business people. It's been argued that oil and gas executives who've funded disinformation about climate change for decades should be chief among them.
Charging individuals for environmental crimes against humanity could be an effective deterrent. But whether the law will develop in time to prosecute people like Bolsonaro is, as yet, uncertain. Until the International Criminal Court prosecutes individuals for crimes against humanity based on their environmental damage, holding individuals criminally accountable for climate change remains unlikely.
This story originally appeared in The Conversation. It is republished here as part of EcoWatch's partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.
By Natalie Hanman
Why are you publishing this book now?
I still feel that the way that we talk about climate change is too compartmentalised, too siloed from the other crises we face. A really strong theme running through the book is the links between it and the crisis of rising white supremacy, the various forms of nationalism and the fact that so many people are being forced from their homelands, and the war that is waged on our attention spans. These are intersecting and interconnecting crises and so the solutions have to be as well.
The book collects essays from the last decade, have you changed your mind about anything?
When I look back, I don't think I placed enough emphasis on the challenge climate change poses to the left. It's more obvious the way the climate crisis challenges a rightwing dominant worldview, and the cult of serious centrism that never wants to do anything big, that's always looking to split the difference. But this is also a challenge to a left worldview that is essentially only interested in redistributing the spoils of extractivism [the process of extracting natural resources from the earth] and not reckoning with the limits of endless consumption.
What's stopping the left doing this?
In a North American context, it's the greatest taboo of all to actually admit that there are going to be limits. You see that in the way Fox News has gone after the Green New Deal – they are coming after your hamburgers! It cuts to the heart of the American dream – every generation gets more than the last, there is always a new frontier to expand to, the whole idea of settler colonial nations like ours. When somebody comes along and says, actually, there are limits, we've got some tough decisions, we need to figure out how to manage what's left, we've got to share equitably – it is a psychic attack. And so the response [on the left] has been to avoid, and say no, no, we're not coming to take away your stuff, there are going to be all kinds of benefits. And there aregoing to be benefits: we'll have more livable cities, we'll have less polluted air, we'll spend less time stuck in traffic, we can design happier, richer lives in so many ways. But we are going to have to contract on the endless, disposable consumption side.
Do you feel encouraged by talk of the Green New Deal?
I feel a tremendous excitement and a sense of relief, that we are finally talking about solutions on the scale of the crisis we face. That we're not talking about a little carbon tax or a cap and trade scheme as a silver bullet. We're talking about transforming our economy. This system is failing the majority of people anyway, which is why we're in this period of such profound political destabilisation – that is giving us the Trumps and the Brexits, and all of these strongman leaders – so why don't we figure out how to change everything from bottom to top, and do it in a way that addresses all of these other crises at the same time? There is every chance we will miss the mark, but every fraction of a degree warming that we are able to hold off is a victory and every policy that we are able to win that makes our societies more humane, the more we will weather the inevitable shocks and storms to come without slipping into barbarism. Because what really terrifies me is what we are seeing at our borders in Europe and North America and Australia – I don't think it's coincidental that the settler colonial states and the countries that are the engines of that colonialism are at the forefront of this. We are seeing the beginnings of the era of climate barbarism. We saw it in Christchurch, we saw it in El Paso, where you have this marrying of white supremacist violence with vicious anti-immigrant racism.
That is one of the most chilling sections of your book: I think that's a link a lot of people haven't made.
This pattern has been clear for a while. White supremacy emerged not just because people felt like thinking up ideas that were going to get a lot of people killed but because it was useful to protect barbaric but highly profitable actions. The age of scientific racism begins alongside the transatlantic slave trade, it is a rationale for that brutality. If we are going to respond to climate change by fortressing our borders, then of course the theories that would justify that, that create these hierarchies of humanity, will come surging back. There have been signs of that for years, but it is getting harder to deny because you have killers who are screaming it from the rooftops.
One criticism you hear about the environment movement is that it is dominated by white people. How do you address that?
When you have a movement that is overwhelmingly representative of the most privileged sector of society then the approach is going to be much more fearful of change, because people who have a lot to lose tend to be more fearful of change, whereas people who have a lot to gain will tend to fight harder for it. That's the big benefit of having an approach to climate change that links it to those so called bread and butter issues: how are we going to get better paid jobs, affordable housing, a way for people to take care of their families?
I have had many conversations with environmentalists over the years where they seem really to believe that by linking fighting climate change with fighting poverty, or fighting for racial justice, it's going to make the fight harder. We have to get out of this "my crisis is bigger than your crisis: first we save the planet and then we fight poverty and racism, and violence against women". That doesn't work. That alienates the people who would fight hardest for change.
This debate has shifted a huge amount in the U.S. because of the leadership of the climate justice movement and because it is congresswomen of colour who are championing the Green New Deal. Alexandria Ocasio-Cortez, Ilhan Omar, Ayanna Pressley and Rashida Tlaibcome from communities that have gotten such a raw deal under the years of neoliberalism and longer, and are determined to represent, truly represent, the interests of those communities. They're not afraid of deep change because their communities desperately need it.
In the book, you write: "The hard truth is that the answer to the question 'What can I, as an individual, do to stop climate change?' is: nothing." Do you still believe that?
In terms of the carbon, the individual decisions that we make are not going to add up to anything like the kind of scale of change that we need. And I do believe that the fact that for so many people it's so much more comfortable to talk about our own personal consumption, than to talk about systemic change, is a product of neoliberalism, that we have been trained to see ourselves as consumers first. To me that's the benefit of bringing up these historical analogies, like the New Deal or the Marshall Plan – it brings our minds back to a time when we were able to think of change on that scale. Because we've been trained to think very small. It is incredibly significant that Greta Thunberg has turned her life into a living emergency.
Yes, she set sail for the UN climate summit in New York on a zero carbon yacht ...
Exactly. But this isn't about what Greta is doing as an individual. It's about what Greta is broadcasting in the choices that she makes as an activist, and I absolutely respect that. I think it's magnificent. She is using the power that she has to broadcast that this is an emergency, and trying to inspire politicians to treat it as an emergency. I don't think anybody is exempt from scrutinising their own decisions and behaviours but I think it is possible to overemphasise the individual choices. I have made a choice – and this has been true since I wrote No Logo, and I started getting these "what should I buy, where should I shop, what are the ethical clothes?" questions. My answer continues to be that I am not a lifestyle adviser, I am not anyone's shopping guru, and I make these decisions in my own life but I'm under no illusion that these decisions are going to make the difference.
Some people are choosing to go on birth strikes. What do you think about that?
I'm happy these discussions are coming into the public domain as opposed to being furtive issues we're afraid to talk about. It's been very isolating for people. It certainly was for me. One of the reasons I waited as long as I did to try and get pregnant, and I would say this to my partner all the time – what, you want to have a Mad Max water warrior fighting with their friends for food and water? It wasn't until I was part of the climate justice movement and I could see a path forward that I could even imagine having a kid. But I would never tell anybody how to answer this most intimate of questions. As a feminist who knows the brutal history of forced sterilisation and the ways in which women's bodies become battle zones when policymakers decide that they are going to try and control population, I think that the idea that there are regulatory solutions when it comes to whether or not to have kids is catastrophically ahistorical. We need to be struggling with our climate grief together and our climate fears together, through whatever decision we decide to make, but the discussion we need to have is how do we build a world so that those kids can have thriving, zero-carbon lives?
Over the summer, you encouraged people to read Richard Powers's novel, The Overstory. Why?
It's been incredibly important to me and I'm happy that so many people have written to me since. What Powers is writing about trees: that trees live in communities and are in communication, and plan and react together, and we've been completely wrong in the way we conceptualise them. It's the same conversation we're having about whether we are going to solve this as individuals or whether we are going to save the collective organism. It's also rare, in good fiction, to valorise activism, to treat it with real respect, failures and all, to acknowledge the heroism of the people who put their bodies on the line. I thought Powers did that in a really extraordinary way.
What are you views on what Extinction Rebellion has achieved?
One thing they have done so well is break us out of this classic campaign model we have been in for a long time, where you tell someone something scary, you ask them to click on something to do something about it, you skip out the whole phase where we need to grieve together and feel together and process what it is that we just saw. Because what I hear a lot from people is, ok, maybe those people back in the 1930s or 40s could organise neighbourhood by neighbourhood or workplace by workplace but we can't. We believe we've been so downgraded as a species that we are incapable of that. The only thing that is going to change that belief is getting face to face, in community, having experiences, off our screens, with one another on the streets and in nature, and winning some things and feeling that power.
You talk about stamina in the book. How do you keep going? Do you feel hopeful?
I have complicated feelings about the hope question. Not a day goes by that I don't have a moment of sheer panic, raw terror, complete conviction that we are doomed, and then I do pull myself out of it. I'm renewed by this new generation that is so determined, so forceful. I'm inspired by the willingness to engage in electoral politics, because my generation, when we were in our 20s and 30s, there was so much suspicion around getting our hands dirty with electoral politics that we lost a lot of opportunities. What gives me the most hope right now is that we've finally got the vision for what we want instead, or at least the first rough draft of it. This is the first time this has happened in my lifetime. And also, I did decide to have kids. I have a seven year old who is so completely obsessed and in love with the natural world. When I think about him, after we've spent an entire summer talking about the role of salmon in feeding the forests where he was born in British Columbia, and how they are linked to the health of the trees and the soil and the bears and the orcas and this entire magnificent ecosystem, and I think about what it would be like to have to tell him that there are no more salmon, it kills me. So that motivates me. And slays me.
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