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What To Know Before Starting A Diet (Based On The Real Science)

Avatar Nutrition Staff

May 8, 2020


The internet is full of phony, confusing information about starting a diet for weight loss.

You could spend years chasing every fad, weird piece of advice, and crazy idea… and the worst part is, you’d probably be right back where you started.

Because here’s the wicked truth about starting a diet: Most diets work [1], but most also fail [2].

Let me explain. When you set out on a fat loss journey, you might think you have one goal: lose fat. That part can be hard, easy, or anything in between. If you’re doing it right (and check out section 2 to find out what that means), you’ll probably succeed, regardless of what diet you pick. But the battle doesn’t really end there, because almost all diets work, but most of them leave you stranded. You reach your ideal weight, your ideal look, or give up at “close enough” and aren’t sure where to go from there.

Whether your diet is motivated by looks or health or both, it doesn’t matter—no one wants to end up right back where they started. That’s why you need to know the things in this article. Attack this beast (the dreaded diet!) with the best weapons, build a new you with the best tools, and don’t suffer unnecessarily along the way. The first three sections give you the Eternal Truths of dieting that you have to know to make this happen; the rest of the article gets into the science and details.

Don’t wander into another diet blind or trusting the myths of fat loss. Have confidence, know where you’re going, and reach real, lasting success along the way.


When Starting A Diet, Consistency Is King

Shocked? Probably not. “Be consistent” is the mental equivalent of “eat your vegetables.” It’s great advice, but it teaches you nothing, and it’s about as helpful as “greens are good!” when you’re staring at an uncooked, grass-tasting pile of kale. Nope—not helpful.

We’re going to put “consistency” into perspective. It’s not a magical quality that people who keep lists and calendars have, and it’s not a boring mantra about “doing the same thing all the time.” Consistency is an average—it’s a commitment to do the right thing most of the time, and to get right back on the horse when you fall.

Most diets are temporary and rigid. For some people, that’s a perfect recipe for fat loss. Get in, lose a few pounds, and get out. But for most of us, when we “get out” again, we’re not any better off than when we started. And that’s because the “nuclear option” that most diets resort to just isn’t consistent: it’s not something you can keep doing, and it doesn’t help you at all when it’s over.

This is really important. Lots of research has looked at how dieters turn out after a year or two, and the results are dismal. Most subjects in weight loss studies manage to lose significant weight (more than 10% of their body’s worth). Now, most diets would raise the flag and call it quits right there—success, right? Not quite. Looking deeper, studies that follow those people after the diet ends find they gain most of that weight right back. About 70% of it, in fact [2].

Diets are simple, but they aren’t as simple as seeing the number on the scale go down and calling it a day. When the diet ends, your progress shouldn’t start disappearing, but that’s exactly what happens. And this holds true even when behavioral changes and coaching come with the diet! As soon as that ended, and the participants were left on their own, they started to gradually slip back toward where they started [3].

What we need—what you need—is consistency. In dieting, that means building a plan (or choosing a system) that helps you keep going. That doesn’t mean restricting your food forever! It just means picking a diet that’s sustainable, that sets you up for success and gives you a plan for what to do on the other side. And, most importantly, it has to be a change you can make for the long haul.

Consistency walks hand-in-hand with Success. You can’t have one without the other, and if you have Consistency, there’s no reason you won’t make it to Success. (Assuming your diet really works … but that’s a talk for the next section.)


Quantity Is More Important Than Quality

We’ve already mentioned the idea of a “smart” diet, so let’s talk about what that means. A good diet—one that actually makes you lose fat—works because you consume fewer calories than you burn.

Fat is energy stored in your body. To lose fat, you have to convince your body it needs to burn it off to survive. Just like you wouldn’t dip into your savings if you’re making bank every month, your body won’t pull from its stores of fat-energy unless it absolutely needs to. That means you have to be in a calorie deficit: eating less energy (food) than your body uses and needs.

Great! All you have to do is eat less and move more—it’s easy! Except it usually doesn’t seem that way. Part of the reason is that most people are (rightly) confused as hell about what they really need to do to lose weight. Avoid this, eat that, drink these, wear these shoes, use this product, follow that program… Diets have been concocted that tell you to do everything from eat only potatoes to (and I’m not kidding here) stare into the freaking sun.

And that confusion is more than “part of the problem.” If you want your diet to actually work (and you do) this might be the most important thing to understand: calories and protein matter, and most everything else doesn’t.

The “fad” diets—where you have to strictly adhere to this or that—have all been weighed, measured, and found wanting. If they trick you into eating fewer calories, they tend to work [4]. But the hidden truth is that all diets, when the calories and protein are the same, work the same—every time [5].

That means your friend who lost 20 lbs on that one diet ate less than they needed to maintain weight. If they were lucky, that diet fed them more protein, and they reaped the rewards (which we’ll talk about soon). But it wasn’t because of the magical properties of low-carb or the fact that they were eating for their blood type… even if that’s why they thought it worked. No—it was because they were sapping energy (in the form of fat) from their body.

Even if you’re dieting for “health” and not “looks,” quantity is still more important: “Why You should Actually Prioritize Quantity Over Quality When Dieting.”


You Don’t Have to Be Miserable to Lose Weight

The truth will set you free. Literally.

So, know this: Calories are the most important part of a diet, and calories come from macronutrients (macros): protein, carbs, and fat. These fragments of your food control your dieting destiny, and you can master them if you track them. An eye-roll or two here is normal: “But I don’t want track macros!” That’s fair—but you have to accept that after you’ve made that decision you’re leaving every other part of your diet, including whether it works or not, up to chance. The macros are there whether you count them or not. Either you control them, or they’ll control you.

Here’s the bright side! Knowing that calories and macros (especially protein) matter the most gives you an enormous amount of freedom. It means you don’t have to give up your favorite foods, it means you don’t have to take a shot in the dark with one weird diet after the next, and most of all it means you don’t have to be miserable. And you can still lose weight.

Many people rail against this idea, thinking you have to suffer to make real progress. Does that sound like science? I hope not.

If you don’t have to avoid your favorite dishes, expel happiness from your life, and charge flaming-sword-first into the darkness, you might (definitely will) be better off in the long-run. So, take this truth and roll with it: Diet in a way that’s sustainable, makes sense, and gets you where you want to go—without killing yourself on the way. How? The sections that follow give you the juicy details.

(This advice might not be for everyone. We all know that person: “I just can’t control myself/stop eating carbs/have just one slice/etc.” The best we can say here is: You have the freedom to not be that person. The choice is yours.)


Protein is the Game-Changer You’ve Been Looking For

It should be clear now that calories matter the most when dieting: If you’re not restricting calories, you’re not going to move energy out of your body, which is the most confusing way to say, “lose weight.” It’s just not possible. But, while calories will control the amount of weight you lose, where those calories come from (macros) will change what kind of weight you lose. And that’s where protein comes in.

It’s worth repeating a thousand times: When you compare diets that are the same in calories and protein, the fat lost is also the same. Calories makes sense, but why protein? Because eating plenty of protein while you diet spares your body from burning through its stores of muscle [7], so more of the weight you lose will be fat. (In the next section, you’ll see why that’s so important.)

And, of all the macronutrients, protein helps you stay the fullest [8]. Eating high-protein foods on a diet helps stave off pesky hunger, keeping you satiated and happy.

(But wait, there’s more!) Protein also has the biggest effect on the thermic effect of food (TEF), which is fancy science for “how much energy you burn while digesting and using the food you eat” [9]. While TEF doesn’t make a huge difference in the total energy you burn each day, stoking the furnace here and there with protein doesn’t hurt!

And the best part might be that high-protein diets have weird, amazing effects. For instance, in a study where subjects overate on pure protein, to the tune of 800 extra calories, they somehow didn’t gain any weight [10]! Not too bad. In another study by the same lab, a 400-calorie surplus of protein caused subjects to lose more fat than a moderate-protein control group [11]. Not bad at all.

(Quick disclaimer: We’re not suggesting you say, “calories be damned!” and gorge yourself on protein. Calories are still more important for weight loss, in general. But you have to admit—protein is cool.)

And it’s crazy that we still need to say this, but high-protein diets are not dangerous or bad for your kidneys (unless you already have a serious kidney disease) [19]. In fact, if there’s ever a food group that’s on your side while dieting, it’s protein.


Maintain Muscle for Long-Term Success

Every unit of muscle has a certain metabolic activity, meaning it burns a certain number of calories just by existing. Adding more muscle (or keeping the muscle you already have) can benefit your metabolism, your diet, and the success of your diet when it’s over.

Muscle isn’t as metabolically active as most other organs—like the heart, brain, or kidneys [12]—but we can’t really make our kidneys bigger to burn fat. (And that wouldn’t’ be a great idea, health-wise.) Muscle is the only major organ-system we can significantly change, which is why muscle is important for sustainable fat loss. At the end of your diet, you don’t want to be worse off (metabolically) than when you started.

If you lose muscle while dieting, you’ll reduce your metabolism. That means the diet itself could get harder (since you’ll have to eat even less to be in a deficit) and maintaining your weight after the diet will be harder, too. Neither of those is great for keeping the pounds off in the long-run. That’s why dieting isn’t just about losing fat—it’s also about not losing muscle. So, how do we do that?

You already know one trick: eat lots of protein [7]. When you’re in a deficit, your body steals protein from muscle tissue to feed other parts of your body, creating hormones and enzymes, rebuilding organs, and generally allowing you to stay alive—which is nice. But if you get enough protein from food, your body will have plenty to work with and won’t have to dip into its “savings,” aka your biceps and glutes.

The other trick for maintaining muscle is exercise. If you put your muscles to work, you’re sending your body a signal that you need that stuff, and it’s not okay to tear it apart. And, when it comes to choosing which type of exercise…


Weights Are Better Than Cardio

Let’s get something out of the way: In the land of dieting, nutrition is queen. (Remember who’s king?!) If you’re not eating a calorie deficit with plenty of protein you’re setting yourself up for failure. But exercise has its place too—in fact, as we saw in the last section, you should exercise while dieting. You’ll expend more calories and, if you do it right, hold onto precious, metabolism-boosting muscle. Science backs this up: Dieters who also exercised maintained more weight loss after a year than those who just dieted or just exercised [13].

But it’s not always as clear what kind of exercise you should be doing. There’s a big debate between the two ends of the spectrum: lifting weights and doing cardio. Which is better for fat loss?


Okay, that’s not a complete answer. Lifting weights doesn’t expend as much energy as cardio, so you could make an argument that cardio is the better driver of fat loss. But exercising while dieting isn’t about burning more fat, it’s about not burning more muscle. And that’s where hitting the weights wins, hands-down.

In one study, subjects dieted on 800 calories for 12 weeks (those poor souls). One group did cardio and the other lifted weights. At the end of the study, the cardio-group lost more weight, but they also lost almost 9 lbs of lean body mass (much of which was likely muscle). By contrast, the resistance training-group lost zero lean body mass. And while the cardio-group’s metabolisms went down, the resistance training-group’s metabolisms actually increased [14].

To learn more, check out “How to Exercise on a Diet Without Losing Muscle.


Smarter Satiety = Happier You

If you’re an alien who never gets hungry, then this section isn’t for you. For our human readers, it’s pretty obvious that hunger is the big problem with dieting. The mantra is “eat less,” and we’re all pretty cool with that first word—it’s the “less” that gives us trouble.

Unfortunately, there’s no way around that. To make serious progress, at some point you’re going to feel hungry—even hangry. But, while we can’t banish hunger completely, we can play it smart and keep it to a minimum. Here’s how:

We already talked about this one: Eat lots of protein. It has such a robust impact on satiety (fullness) that scientists think protein-induced satiety can cause weight loss on its own, by making you eat less [8]. Yes, protein is awesome.

You can also make sure you’re getting plenty of fiber. Although some research questions whether fiber makes a big difference in fullness [15], soluble fiber options like oats have long been touted as great diet foods because they digest slowly and keep you fuller, longer [16].

Finally, eating foods with high “volume” will improve satiety [17]. Simply put, high-volume foods take up more space in your stomach than lower-volume foods, given the same amount of energy. For instance, 500 calories of popcorn fill you up better than 500 calories of jelly beans.

For the best hunger-kicking firepower, put all of them together and space them out. For every low-calorie meal you have to scarf down while dieting, make sure it has at least two of these boxes ticked: high protein, high fiber, or high volume. With these tricks, you can fill the void in your stomach a few hours longer every day. That makes a big difference in consistency and success.


Keep it Slow & Steady

This is a big one. Up to this point, you may think dieting takes somewhere between 21 days and six weeks. It’s no surprise: most “health and fitness” magazines, fad diets, and gurus try to sell us on quick-and-dirty fat loss. But all of that is utter nonsense.

The reality (for most of us) is that it’s going to take much longer than that. And who is surprised? How many people—no, not counting infomercials—have actually reached success on a 4-Week Belly-Fat-Shredding Fast-Track to Trim? How many, instead, have tried quick fad diets over, and over, and over until they gave up?

Exactly. It took a long time to get where you are, and it’s going to take a while to get where you’re going.

Let’s bring science into this…

At slow rates of dieting—when you’re in a slight deficit, but not far away from maintenance—you can chip away at your body’s fat stores piece by piece without sacrificing muscle tissue [18]. The exact point where you start to drop too low and start burning muscle is different for everyone. (If we knew our sweet spot, dieting would be easy: track macros, eat XYZ calories, exercise, done. Unfortunately, metabolisms change over time, and that sweet spot moves around.)

On the flip side, you have rapid weight loss, the nuclear option: drop calories extremely low, lose a bunch of weight, and call it quits. It sounds great, but it’s a bad idea. Trying to lose the same amount of weight with a faster diet leads to the same weight loss, but much more of it will be lost muscle [21]. As we’ve seen, this can wreak havoc on your long-term success.

The takeaway here is: slow and steady wins the race. Diet slowly, methodically, and with an eye on sustainability instead of speed. Your future self thanks you.


Everything Else Doesn’t Matter

Sure, the type of fats you eat might affect your heart health, you need vitamins and minerals to survive, you should drink enough water… etc. Other things matter besides restricting calories and counting macros. But, for most people trying to lose weight, all the things you thought made a difference probably don’t.

Here’s a list of some things that don’t matter:

I know: this part might get feisty. Lots of people have lots of powerful feelings about lots of the things listed there. “They have to matter!” Why? “Because I spent so much time caring about them!”

Well, unfortunately, no.

It’s tempting to want a sexier, zestier diet. Maybe we’d rather suffer, or maybe we want something awesome to tell our friends when they ask how we got that summer bod. “I just ate grapefruit ‘til I was skinny” is way more interesting than “I tracked and hit my macros until I smartly and sustainably reached my goal.” We admit that. But the second option is the one that works—it’s backed by confident science and it’s the answer your friends probably need to see and hear.

Ignore the nonsense. Save your energy and precious time. Do it for you, and for everyone who will see you as a shining example.


How Long YOU Should Diet

Lots of studies have looked at lots of diets, lasting anywhere from a few weeks to several years, and there doesn’t seem to be a definite golden ratio for how long someone should diet. But that’s not really the question: How long should YOU diet? Now we’re cooking.

We know that diets can be too fast [21], but, if you’re committed to taking your time, when should you stop? Let’s keep it simple: Stop when you’ve reached your goal (genius, we know) or when you see the warnings signs telling you to. Here are the bright red flags that indicate you should consider ending your cut, starting a reverse diet (next section!), and living to burn fat another day:

  • You’ve hit a weight loss plateau, despite hitting your macros consistently for several weeks
  • You’re constantly hungry and fighting the urge to overeat
  • You’re cycling between over-restricting and binging, making no progress and suffering for it

Some people can diet for eight or nine months without hitting these roadblocks, while others struggle after just a few weeks. It’s different for everyone, and you’ll have to pay close attention to your body.

And, whether you crushed your goal (congrats!) or need to step back from dieting to make more progress later (smart!), your next step should always be reverse dieting.


The Reverse Diet—Finally, a Happy Ending

Even a perfect diet can be ruined by what you do after—that’s why the rate of weight regain is sky-high [2]. With any luck, you’re stepping out of your deficit having lost a good amount of fat, a minimal amount of muscle, and a healthy metabolism. But very few of us are lucky enough to walk away unscathed.

Diets will almost always slow down your metabolism. Your weight has gone down, you’ve lost some muscle, and your body has slowly adapted to eat less food. That means you’re primed to gain weight back—but we’re not going to let you. We have a way out, and it’s called reverse dieting.

Reverse dieting (or “reversing”) is the process of getting to the good stuff (eating more) a bit more slowly. By gradually increasing your calories each week, your body can steadily ramp-up its metabolism back to its pre-dieting glory… sometimes better! A reverse sets you up for the long-term, sustainable success we’ve been pushing this whole time.

There’s a lot more to say about this, so check out “The Complete Guide to Reverse Dieting.


The Next Step Is Forever

The simple, negative, unhelpful truth is that most diets fail. But most diets fail because most people care more about finishing a diet than whether it makes sense and sets them up for success. Now you know everything you need to be the exception. Be consistent, follow the science, and never turn back. Forever starts here.

Interested in learning more? Follow us on Facebook, Instagram, Pinterest, and Youtube for more tips!




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