How do the Seventh Day Adventist approach Old Testament laws?

Seventh Day Adventists's do not base their teachings on health on OT laws. They do, however, generally follow the concept of clean and unclean meat found in Leviticus, if they are Omnivores. Those who follow the health guidelines are Vegetarians, this comes from the original creation diet and also the diet of Daniel. This is also endorsed be Ellen White, who had the gift of prophecy.

It is also important to note that being a vegetarian is not a requirement or belief. Adventists believe that they ought to look after their body to better serve God and the community. It is also a useful tool to engage people who are looking for a healthy lifestyle to enable them than to share Christ and how he works on hearts as well.This is stated in the fundamental belief on Christian behaviour. https://www.adventist.org/en/beliefs/living/christian-behavior/

It also means that because our bodies are the temples of the Holy Spirit, we are to care for them intelligently. Along with adequate exercise and rest, we are to adopt the most healthful diet possible and abstain from the unclean foods identified in the Scriptures. Since alcoholic beverages, tobacco, and the irresponsible use of drugs and narcotics are harmful to our bodies, we are to abstain from them as well. Instead, we are to engage in whatever brings our thoughts and bodies into the discipline of Christ, who desires our wholesomeness, joy, and goodness.

Regarding other laws in the old testament, Adventists would subscribe to the idea that they persist through the death of Christ. That Christ did not abolish the law but came as a perfect sacrifice. Therefore fulfilling the sacrificial laws, but not abolishing Gods laws. The most notable are the ten commandments, which includes remembering the Sabbath as the fourth commandment, which is where the Seventh Day Adventists get their name. Once again this is articulated in the belief statements. https://www.adventist.org/en/beliefs/living/the-law-of-god/

The great principles of God’s law are embodied in the Ten Commandments and exemplified in the life of Christ. They express God’s love, will, and purposes concerning human conduct and relationships and are binding upon all people in every age. These precepts are the basis of God’s covenant with His people and the standard in God’s judgment

As a seventh day Adventist, I find confidence in this idea when Jesus says. "For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished." Matthew 5:18

First, about the dietary guidelines: they are based on Genesis, not Leviticus; in other words, they don't stop at Moses, but rather go all the way back to Eden.

Adventists don't follow any of the Levitical laws as such (though there is a small group that believes we should). We sometimes refer to portions of Leviticus because the founders of the denomination convinced the church, through reason and scripture, that specific portions of it are still relevant.

In my own words: when the Israelites were given the Ten Commandments, they said "do not let God speak to us" and “Everything the Lord has said we will do”, instead of a simple "thank you". Essentially, they misunderstood "you shall" as "you must", causing Moses to write down the law in more detail (in Leviticus), and were later given 490 years to make an end of transgressions, which, being mere humans, they were unable to do: we need God to accomplish that within us.

Adventists, on the other hand, do not consider these laws (even the ones we like to quote, such as the clean/unclean animals) to be binding in every detail. They were an application of the law to their culture, their needs, and their level of knowledge.

As for the Ten Commandments, the Adventist Church definitely considers them to be more holy than the lesser laws; they were written in stone by the finger of God and are a transcript of His character (p.434). They are timeless, they cross the cultural boundaries; we believe it is the Ten Commandments which Paul says are "written in the hearts" of those who "do instinctively the things of the Law" (Romans 2:14, 15).

We Seventh Day Adventists distinguish between three different kinds of laws in the Bible:

1. Moral laws.
2. Ceremonial laws.
3. We also believe that there were laws in the OT specific to Israel as a nation. Something like their "civil code".

(Strictly speaking, there are also a few descriptions of other nations' laws in some books, like Persian laws in Daniel, or Roman laws in the NT; but these have nothing to do with theology or with laws given by God to His people.)

First, let me say that for us, the only laws that apply today are the Moral laws. But this poses at least two more questions:

1. How do we distinguish between the three types of laws?
2. Why, if the ceremonial laws do not apply anymore, are we still not eating some meals?

I will do my best to briefly answer these questions:

1. Distinction

The moral laws are the Ten Commandments (Exodus 20 and Deuteronomy 5). They are different from any other laws in the OT in at least the following aspects:

• Although beautifully synthesized in the Ten Commandments, all of them are supported by the Bible as a whole. For example, Adventists believe that the Sabbath of the Fourth Commandment started with the Creation (Genesis 2:1-3), and thus it was given to mankind and not just to Israel. I mention the Sabbath because most Christians will probably agree on the other nine as perfectly valid today (probably with some different points of views, mainly from the Roman Catholic Church regarding the Second Commandment). There is a lot to write about the Sabbath and why it's still important today, but that's better for a different, new question.
• They were written by God Himself in stone and given to Moses (Exodus 31:18 and 32:16).
• Those were the only laws in the Ark of the Covenant (2 Chronicles 5:10, Hebrews 9:4). That's in relation with Adventists' unique fundamental belief of the Sanctuary, which is probably the most distinctive doctrine in Adventism.
• They will apply after the Second Coming of Jesus, as they are the base of God's government (Revelation 22:14, Isaiah 66:22-23).
• The Law of God is of such importance that it required Jesus to die for us, as the Only Means of Salvation. In other words, His law is absolutely immutable, so not even God will change it, giving his only Son instead (John 3:16).

On the other hand, the ceremonial laws were only of importance in the context of giving the OT people the best possible understanding of God's plan of salvation. This is also better understood (in an Adventist context) through the belief of the Sanctuary. These, and only these laws, according to Adventism, were abolished in the cross.

Finally, regarding the laws that were only regulating OT Israel's life as a nation under the theocracy (although were applied too under certain kings—not all—during the Monarchy), probably most Christians will agree that those were given only for that context and that they are easy to distinguish even from ceremonial laws. Jesus even mentioned that some of them were given to Israel "because of the hardness of your hearts" (Mathew 19:8). For most Adventists interpreters, these laws have a relation with our fundamental belief of the Present Truth (a topic that would exceed this question).

2. Health and OT laws:

The idea that we extract our health practices (barely the only practices in relation with the OT laws that aren't part of the moral law) from the OT ceremonial or "civil" laws is a misunderstanding of Adventism. In fact, a lot of Adventists are vegetarians simply because our idea is that God created us (and the animals—yes, our view of Creation is a bit different too) as vegetarians (Genesis 1:29-30, 2:9). That's present in other portions of the Bible, in relation with health (see Daniel 1:8-20). For example, Ellen White wrote about the people living before the Flood:

"They loved to destroy the lives of animals. They used them for food, and this increased their ferocity and violence, and caused them to look upon the blood of human beings with astonishing indifference." (Spirit of Prophecy, p. 69)

There are plenty of other White's statements about food and health (see Ellen G. White's Message on Health)

So for us, God authorized at some point to eat some meats, but that does not mean that that was His original plan at all. And the "authorized" meat was, in our view, the "less unhealthy". Also, it's worth noting that the distinction between clean and unclean animals appears much earlier in the Bible than when Israel's laws were given, as the clean animals are in the Flood story, supernaturally selected by God in bigger quantity to enter the Ark, as stated in Genesis 7:2:

Of every clean beast thou shalt take to thee by sevens, the male and his female: and of beasts that are not clean by two, the male and his female.

So for Adventists who are not vegetarians, the OT food laws act as the guide, although a lot of us do understand that our duty is to become vegetarians. But please note that this is not the understanding of all Adventists, so our consensus is to at least, follow OT rules regarding food.

Finally, this page may be of help describing our 6 Doctrines and our 28 Fundamental Beliefs, including taking care of our bodies as a Temple for the Holy Spirit (1 Corinthians 6:19-20): www.adventist.org -> Beliefs.